Can You Really Get a Flu Shot If You Are Allergic to Eggs?

Are you still worried about your child’s egg allergy and getting them a flu vaccine?

Everyone needs a flu shot. When will you get yours?
Everyone needs a flu shot. Even kids with egg allergies. Photo by Gabriel Saldana (CC BY-SA 2.0)

That’s not surprising, as we once warned people about residual egg proteins in flu vaccines and the possibility of immediate hypersensitivity reactions in those with severe egg allergies.

Flu Vaccines and Egg Allergies

Of course, that advice has now changed, even though most flu vaccines are still prepared in chicken eggs.

“Recent studies have shown that even individuals with confirmed egg allergy can safely receive the flu vaccine. The Joint Task Force on Practice Parameters of the American Academy of Allergy Asthma and Immunology and the American College of Allergy Asthma and Immunology as well as the American Academy of Pediatrics state that no special precautions are required for the administration of influenza vaccine to egg-allergic patients no matter how severe the egg allergy.”

Egg Allergy and the Flu Vaccine

In fact, it began to change in 2011, when we got the recommendation that it was okay to give flu shots to people with egg allergies, if they only get hives as their reaction. It was still recommended that those with more severe allergic reactions to eggs “be referred to a physician with expertise in the management of allergic conditions for further risk assessment before receipt of vaccine.”

Before that, we would sometimes do skin testing on high risk egg allergic kids, desensitization, or regular chemoprophylaxis.

In 2013, the recommendation changed so that those with severe allergic reactions to eggs should get their flu shot “by a physician with experience in the recognition and management of severe allergic conditions.”

The recommendations were again modified in 2016, removing the recommendation that egg-allergic flu vaccine recipients be observed for 30 minutes and that those with severe egg allergies “should be vaccinated in an inpatient or outpatient medical setting (including but not necessarily limited to hospitals, clinics, health departments, and physician offices), under the supervision of a health care provider who is able to recognize and manage severe allergic conditions.”

Why the changing advice?

It’s because severe allergic reactions to vaccine are rare (in a million doses rare). And even in the flu vaccines that still use eggs, almost all of the egg protein is removed from the final vaccine. So that residual amount of egg protein is unlikely to trigger an allergic reaction. And that’s what we saw as the recommendations were slowly changed year after year.

Getting a Flu Shot When You Are Allergic to Eggs

And that’s why we have our current recommendations:

  • Those with a history of egg allergy who only get hives can get any age-appropriate flu vaccine.
  • Those with a history of egg allergy who have severe reactions, including angioedema, respiratory distress, lightheadedness, recurrent emesis, or who required epinephrine or another emergency medical interventions, can still get any age-appropriate flu vaccine, but they should get it in an inpatient or outpatient medical setting (such as a hospital, clinic, health department, or physician’s office). And the vaccine administration should be supervised by a health care provider who is able to recognize and manage severe allergic reactions.
  • Those who can eat eggs without reaction can get any age-appropriate flu vaccine.

Do you still have to be observed after getting your flu vaccine if you have an egg allergy?

No postvaccination observation period is recommended specifically for egg-allergic persons.

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season

Nope. But that’s likely because although they are rare, reactions might not occur right away.

So yes, you can and you should get a flu vaccine if you are allergic to eggs.

More on Flu Vaccines and Egg Allergies

 

Crisis at the Nordic Cochrane Centre

This could be it for the Nordic Cochrane Centre.

“I regret to inform you that I have been expelled from membership in the Cochrane Collaboration by the favourable vote of 6 of the 13 members of the Governing Board. No clear reasoned justification has been given for my expulsion aside from accusing me of causing “disrepute” for the organization.”

Peter Gøtzsche on A moral governance crisis: the growing lack of democratic collaboration and scientific pluralism in Cochrane

Or at least for Peter Gøtzsche and his association with the Cochrane Collaboration, which he co-founded in 1993.

I’m not sure how he thinks that there was no clear justification for his being expelled though.

Crisis at the Nordic Cochrane Centre

Most folks understand why Peter Gøtzsche was expelled from the Cochrane Collaboration…

They remember that he recently published a poorly done analysis in BMJ Evidence-Based Medicine, The Cochrane HPV vaccine review was incomplete and ignored important evidence of bias that was critical of a Cochrane Review on the HPV vaccine, Prophylactic vaccination against human papillomaviruses to prevent cervical cancer and its precursors, which concluded that the HPV vaccines work and that they are safe.

While Gøtzsche’s analysis prompted the Cochrane Collaboration to initiate an investigation, they concluded that his analysis “substantially overstated its criticisms” and that the allegations were “not warranted and provided an inaccurate and sensationalized report of their analysis.”

Is that it?

Nope.

Many people are also familiar with the Nordic Cochrane Centre because of their involvement in continued complaints about the HPV vaccine. Complaints that were not approved by the Cochrane Collaboration and that were not an official Cochrane viewpoint!

“…we highlight here how academic colleagues, under the purported banner of a respected authority, raise concerns about the HPV vaccine but they cite an evidence base of small and poor quality studies and ignore the extensive wealth of global literature that vividly demonstrate the excellent efficacy and safety record of the vaccine.”

Head et al on Inadvisable anti-vaccination sentiment: Human Papilloma Virus immunisation falsely under the microscope

Complaints that had already been investigated and dismissed by the European Medicines Agency and refuted by many other studies.

“This week at its meeting in Edinburgh, Cochrane’s Governing Board considered, as planned, the findings of an independent review and additional complaints related to the conduct of a Member. The Board’s conclusion was communicated to the individual concerned and is part of an ongoing process. The Co-Chairs of the Board will provide further details once this process is complete.

Following this, four Board members (Gerald Gartlehner, David Hammerstein Mintz, Joerg Meerpohl and Nancy Santesso) decided to resign as Cochrane trustees with immediate effect.”

Message from the Governing Board

Unfortunately, Gøtzsche’s being expelled led to others leaving the Cochrane Governing Board, including two appointed trustees who volunteered to step down to to comply with Cochrane’s Articles of Association.

Although they may not have been defending Gøtzsche's opinions or behaviors, four other board members resigned in solidarity.
Although they may not have been defending Gøtzsche’s opinions or behaviors, four other board members resigned in solidarity.

We can hope that this is the end of the matter, as Cochrane will soon have an election for new board members.

Peter Gøtzsche is out at the Cochrane Collaboration.
Peter Gøtzsche is out at the Cochrane Collaboration.

Will he be kept on at the Nordic Cochrane Centre, which he founded? Will the Nordic Cochrane Centre be allowed to keep ‘Cochrane’ in their name?

The Nordic Cochrane Centre is primarily funded by the Danish Government, and what do they get besides all of the anti-HPV vaccine stuff?

“Antidepressant drugs are another major killer that people could do well without.”

Peter C Gøtzsche: Prescription drugs are the third leading cause of death

Peter Gøtzsche seems to be against cancer screening, psychiatric drugs, and thinks that Big Pharma has corrupted health care. Is that the “plurality of opinions, views, and perspectives” that folks want at Cochrane or anywhere else in medicine?

Unfortunately, I bet this isn’t the last that we have heard from him.

More on the Crisis at the Nordic Cochrane Centre

Which Flu Vaccine Should You Get?

After decades with a single type of flu vaccine – the flu shot – there are now many different kinds of flu vaccines that many of us can choose from. And your choices are not just between the nasal spray flu vaccine vs a flu shot. There are also a lot of different kinds of flu shots available now.

Everyone needs a flu shot. When will you get yours?
Everyone needs a flu shot. When will you get yours? Photo by Gabriel Saldana (CC BY-SA 2.0)

Having choices is nice.

It would be also be nice to have a little more guidance on what to do with these choices.

Are any of the flu vaccines better than others?

Which Flu Vaccine Should You Get?

This year, we will have:

  • quadrivalent flu shots – Afluria, Fluarix, FluLaval, Fluzone, Fluzone Pediatric Dose
  • quadrivalent flu shots that are cell-culture based – Flucelvax
  • quadrivalent flu shots that can be given intradermally – Fluzone Intradermal
  • trivalent flu shots – Afluria
  • trivalent flu shots that are adjuvanted – Fluad
  • high dose trivalent flu shots – Fluzone High-Dose
  • quadrivalent flu shots that are made with recombinant technology – Flublok
  • nasal spray flu vaccine – Flumist

Which one should you get?

It is actually easy to start by asking which one you should get for your kids, as many of these flu vaccine options are only available for adults and seniors.

Flu Vaccine Options

Before you start thinking too long and hard about potential options, keep in mind that you might not have as many options as you think.

“Not all products are likely to be uniformly available in any practice setting or locality. Vaccination should not be delayed in order to obtain a specific product when an appropriate one is already available.”

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season

Doctors and clinics might not stock multiple brands or types of flu vaccines, so you might have to get whatever flu vaccine that they have available.

“Within these guidelines and approved indications, where more than one type of vaccine is appropriate and available, no preferential recommendation is made for use of any influenza vaccine product over another.”

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season

And that’s okay. In most cases, there haven’t been head to head studies showing that one flu vaccine is better than another.

Flu Vaccine Options for Kids

Still, since these options might be available to you, it is good to know about them.

This year, younger kids, between the ages of 6 months and 3 years, can either get:

  • FluLaval Quadrilvalent
  • Fluarix Quadrivalent
  • Fluzone Quadrivalent Pediatric

While you are unlikely to notice a difference, both FluLaval and Fluarix are given at a 0.5ml dose containing 15 µg of HA per vaccine virus, while Fluzone is given at a 0.25ml dose containing 7.5 µg of HA per vaccine virus. Why the difference? “Safety and reactogenicity were similar between the two vaccines,” even at the different doses.

Basically, these are just different brands of the same type of flu shot.

There are even more options as your kids get older though, including  Fluzone Quadrivalent (age three and above), Afluria Quadrivalent or Trivalent (age five and above), Flucelvax Quadrivalent (age four and above), FluLaval and Fluarix.

Of these, some folks wonder if Flucelvax, since it isn’t made in chicken eggs, might be more effective than the others. Remember, one of the things that are thought to make the flu vaccine less effective than most other vaccines is that they are made in eggs, leading to mutations. And there is actually some evidence that those flu vaccines that are not made in eggs might be more effective.

“And the University of Pittsburgh Medical Center is taking that a step further, saying it will only be buying the two egg-free vaccines on the market: Flucelvax and FluBlok. That’s because there is some evidence these two formulations may work better than the older vaccines grown in eggs, said Dr. Richard Zimmerman, who advises the UPMC Influenza Committee.”

Guidance on which flu vaccine to get: Shots for kids, maybe go egg-free

Again, remember that the CDC has made “no preferential recommendation” for one flu vaccine over another. Why not? We don’t have enough information to make that kind of recommendation.

Should parents only ask for Flucelvax? That would only work if they made enough doses for every kid to get vaccinated, which they didn’t. Should you hold out until you can find FluceIvax for your kids? No, since doing that might leave them unvaccinated once flu season hits.

What else should you know about your flu vaccine options? While over 80% of flu vaccines are now thimerosal free, most of these flu vaccines are still available in multi-dose vials with thimerosal.

Also thimerosal free, this year, Flumist is back as an option. It is available for healthy kids who are at least two years old. Although the AAP has issued a preference for flu shots this year, the ACIP says that kids can get either Flumist or a flu shot.

What about if your kids are allergic to eggs?

“Persons who report having had reactions to egg involving symptoms other than urticaria (hives), such as angioedema, respiratory distress, lightheadedness, or recurrent emesis; or who required epinephrine or another emergency medical intervention, may similarly receive any licensed, recommended, and age-appropriate influenza vaccine (i.e., any IIV, RIV4, or LAIV4) that is otherwise appropriate for their health status.”

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season

Unless they had a severe allergic reaction to a previous flu vaccine, they can get any available flu vaccine, especially if the previous reaction was only hives or they are able to eat eggs.

What if you want a flu vaccine without aluminum? Take your pick. While it would be safe it was, aluminum is not an ingredient in flu vaccines.

Flu Vaccine Options for Adults

In addition to all of the flu vaccines available for older kids, adults have a few more options:

  • Afluria Quadrivalent or Trivalent can be given by jet injector  to those between the ages of 18 and 64 years
  • Flublok Quadrivalent – a recombinant flu shot that can be given to those who are at least 19 years old
  • Fluzone High-Dose – a trivalent flu shot with a higher dose of flu virus antigens (4 times the amount of antigen as a regular flu shot) that is available for seniors who are at least 65 years old
  • Fluad – a trivalent flu shot with an adjuvant that is available for seniors who are at least 65 years old

Why get a flu vaccine with a jet injector instead of a standard needle? High-pressure jet injectors don’t use needles!

Like FluceIvax, Flublok is not made in chicken eggs. The recombinant hemagglutinin(HA) proteins are made in insect cell lines. Does Flublok work better than egg based flu vaccines? That’s the theory, but again, there is no preference for one of these vaccines over another.

Seniors have even more choices.

Should they get Fluzone High-Dose, Fluad, or one of the other flu vaccines? Both have been shown to be more effective than standard flu vaccines in seniors, but they have not been compared against each other.

“In a Canadian observational study of 282 people aged 65 years and older conducted during the 2011-12 season, Fluad was 63% more effective than regular-dose unadjuvanted flu shots.”

CDC on People 65 Years and Older & Influenza

But neither Fluzone High-Dose nor Fluad are quadrivalent, so only protect against three flu virus strains.

Is there a quadrivalent flu shot for older adults that might work better than standard flu shots?

Yes. FluceIvax and Flublok are non-egg based quadrivalent flu shots that might be more effective than standard flu vaccines.

So are you more confused now that you know you have so many options? Just remember that for most people, the mistake isn’t about choosing the right flu vaccine, it is about not getting vaccinated.

What to Know About Your Flu Vaccine Options

While it might seem like you have a lot more options in a flu vaccine this year and that some might be more effective than others, keep in mind that availability will likely greatly limit these “options.”

And the best flu vaccine is the one that you actually get, as it will be the one that reduces your risk of getting the flu. Missing your chance to get vaccinated and protected because you are waiting for a specific brand or type of flu vaccine isn’t going to help keep the flu away.

More on Your Flu Vaccine Options

Can Flu Shots Cause the Flu?

Most folks get a flu shot each year.

Most, but not all.

Some people still think that getting a flu shot will cause them to have the flu.
Some people still think that getting a flu shot will cause them to have the flu.

Why do some people skip it?

Can Flu Shots Cause the Flu?

Yes, some people think that getting a flu shot will actually cause them to get the flu.

It’s not hard to see why though.

The flu vaccine is not the most effective vaccine we have, so it is certainly possible that you can still get sick with the flu even though you have had your flu vaccine. Of course, that’s not a good reason to skip getting a flu vaccine, as they have lots of benefits.

Some other reasons you might still think that the flu vaccine can cause the flu include that:

  • side effects after a flu shot can include a soreness, low-grade fever, headache and muscle aches, which some people might confuse with a mild case of the flu
  • many other respiratory viruses can make you sick during cold and flu season, none of which the flu vaccine protects you against
  • since the flu vaccine takes about two weeks to work, if you got sick shortly after being vaccinated, you may have already been exposed and developed the flu before the vaccine became effective

But why can’t the flu shot cause the flu?

That’s easy.

It’s because the flu shot is an inactivated vaccine. The influenza virus is killed or inactivated, the viral particles are purified and split up, with only the HA and NA surface glycoproteins remaining. Those glycoproteins can not cause a natural flu infection.

What about Flumist, the nasal spray flu vaccine?

While Flumist is a live virus vaccine, it is made with attenuated or weakened strains of the flu that are cold-adapted, unable to replicate at the warmer temperatures that are found in the lungs and other areas of our bodies.

So Flumist doesn’t cause the flu either.

Hopefully this is one vaccine myth that folks will stop spreading. Remember, flu vaccines don’t cause you to get sick with the flu. Get vaccinated. Flu vaccines are your best protection against the flu.

What about those folks who say that they are going to skip the flu shot because they never get sick with the flu?

They are gambling.

It is estimated that about 5 to 20% of people get the flu each year. Unless you are rarely around other people during flu season, the chances are that you will eventually get the flu, especially if you are unvaccinated and unprotected.

More on the Myth that Flu Shots Cause the Flu

Are Your Kids at High Risk for Flu Complications?

Everyone should get a flu vaccine each year, as long as they are at least six months old and have no true contraindications.

Everyone needs a flu shot. When will you get yours?
Everyone needs a flu shot. When will you get yours? Photo by Gabriel Saldana (CC BY-SA 2.0)

That has been the recommendation since at least the 2010-11 flu season.

And while most kids get vaccinated, not all do.

Are Your Kids at High Risk for Flu Complications?

There are some kids, those at high risk for flu complications, who definitely shouldn’t skip or delay their flu vaccine.

  • all children aged 6 through 59 months (younger than age 5 years);
  • children who have chronic medical conditions, including pulmonary (such as asthma and cystic fibrosis), cardiovascular (excluding isolated hypertension), genetic (Down syndrome), renal, hepatic, neurologic (cerebral palsy, epilepsy, stroke, muscular dystrophy, and spina bifida, etc.), hematologic (sickle cell disease), or metabolic disorders (including diabetes mellitus and mitochondrial disorders);
  • children who are immunocompromised due to any cause (including immunosuppression caused by medications or by HIV infection);
  • teens who are or will be pregnant during the influenza season;
  • children and adolescents (aged 6 months through 18 years) who are receiving aspirin- or salicylate-containing medications (like for Kawasaki disease) and who might be at risk for experiencing Reye syndrome after influenza virus infection;
  • residents of nursing homes and other long-term care facilities;
  • American Indians/Alaska Natives;
  • children who are extremely obese (body mass index ≥40).

You also shouldn’t skip or delay getting a flu vaccine if your:

  • kids are household contacts of children aged ≤59 months (i.e., aged <5 years) and adults aged ≥50 years, particularly contacts of children aged <6 months;
  • kids are household contacts of someone with a medical condition that puts them at higher risk for severe complications from influenza.

Again, since everyone should get a flu vaccine, these higher risk classes shouldn’t determine whether or not you vaccinate your kids, but they might influence the timing.

Again, don’t skip your child’s flu vaccine because they aren’t in a flu high risk group.

In most flu seasons, about 80% of children with the flu who die are not vaccinated. And many of them will be otherwise healthy, without an underlying high risk medical condition.

Get your child vaccinated against the flu. And if they are in a high risk group, make sure you do it well before flu season starts and maybe as soon as flu vaccine becomes available in your area.

More on Being at High Risk for Flu Complications

Why Are the DPT and OPV Vaccines Still Used in Some Countries?

As most folks know, neither the DPT nor OPV vaccines are used in the United States.

Pope Francis helped launch a polio vaccine campaign when he visited Mexico in 2016.
Pope Francis helped launch a polio vaccine campaign when he visited Mexico in 2016.

That they are still used in other countries likely raises some questions for those folks that get them.

Why Are the DPT and OPV Vaccines Still Used in Some Countries?

As I am sure you have guessed, there is no conspiracy about the continued use of these vaccines in other parts of the world. We aren’t getting rid of old stocks of vaccines or using cheaper vaccines in poorer parts of the world.

So what’s the reason?

To understand why they are still used in other countries, it helps to understand why they aren’t used here.

Remember that the DPT vaccine, which protects folks against diphtheria, pertussis, and tetanus, came under attack in the 1970s and 80s as some folks blamed the vaccine for causing vaccine injuries, including seizures and encephalopathy. It didn’t, but we still got a new vaccine, DTaP, which doesn’t seem to work as well.

“Although concerns about possible adverse events following their administration have led to the adoption of acellular pertussis vaccines in some countries, whole-cell pertussis vaccines are still widely produced and used globally in both developed and developing countries. Whole-cell pertussis vaccines that comply with WHO requirements, administered according to an optimal schedule have a long and successful record in the control of whooping cough. Furthermore, the excellent efficacy of some currently available whole-cell pertussis vaccine has also been shown, not only in recent clinical trials, but also on the basis of the resurgence of disease where vaccination has been interrupted or when coverage has markedly decreased. Therefore, WHO continues to recommend whole-cell pertussis vaccines for use in national immunization programmes.”

WHO on Recommendations for whole-cell pertussis vaccine

The WHO now recommends that if countries do switch to DTaP,  the acellular pertussis vaccine, they should be prepared to add additional periodic booster doses and immunizations during pregnancy, which may still “may not be sufficient to prevent resurgence of pertussis.”

The OPV vaccine, on the other hand, was replaced because it can rarely cause vaccine-associated paralytic polio (VAPP) and circulating vaccine-derived polio virus (cVDPV). Of course, it does it at much lower rates than wild polio virus, so until polio is well controlled, the benefit of using OPV outweighs the risk. In addition to being less expensive and easier to use, OPV has the benefit over IPV of providing better herd immunity.

At some point, as we did in the United States in 2000, countries make a switch to the IPV vaccine.

In 2016, remaining countries that use OPV switched from trivalent OPV to bivalent OPV, because wild polio virus type 2 was eradicated in 1999. Once the remaining two types are eradicated, we can stop using the OPV vaccine altogether.

Until then, countries either use:

  • OPV plus one dose of IPV
  • sequential IPV-OPV schedules – high vaccine coverage and low risk of wild polio importation
  • IPV only schedules – sustained high vaccine coverage and very low risk of wild polio importation

So there is no conspiracy. These vaccines are safe and they work.

Without them, there would be over:

  • 1.3 million pertussis related deaths each year
  • 600,000 cases of paralytic polio each year

With most of these cases affecting young children.

More on the Continued Use of DPT and OPV Vaccines

How Contagious Is Measles?

Did you hear about the folks in New York who got quarantined isolated on the Emirates plane from Dubai?

Turns out that about 10 passengers had the flu or other cold viruses.
Although the worry was likely about MERS, it turns out that about 19 passengers had the flu or other cold viruses.

News like that and folks getting exposed to other infectious diseases, probably has them wondering just how contagious these diseases are. Do you have to be sitting next to someone to get them? In the same row? On the same floor?

Understanding Your Risk of Catching a Disease

Fortunately, most diseases are not terribly contagious.

We worry about some things, like SARS and Ebola, because they are so deadly, not because they are so contagious or infectious.

Wait, contagious or infectious? Aren’t they the same thing?

To confuse matters, some infectious diseases aren’t contagious, like Lyme disease. And some vaccine-preventable diseases are neither infectious nor communicable. Think tetanus. You may have never thought of it that way, but you aren’t going to catch tetanus from another person. Of course, that’s not a good reason to skip getting a tetanus shot!

To understand your risk of getting sick, you want to understand a few terms, including:

  • infectious disease – a disease that can be transferred to a new host
  • communicable – an infectious disease that can be transferred from one host to another
  • non-communicable – a non-infectious disease which can not be transferred from one host to another
  • contagiousness – an infectious disease that is easily transferred from one person to another
  • infectivity – the ability of an infectious agent to cause an infection, measured as the proportion of persons exposed to an infectious agent who become infected. Although this doesn’t sound much different from contagiousness, it is. The Francisella tularensis bacteria is highly infectious, for example, to the point that folks exposed to a culture plate are given antibiotics or put on a fever watch. Few of us get tularemia though, because transmission is through tick bites, hunting or skinning infected rabbits, muskrats, prairie dogs and other rodents, or inhaling dust or aerosols contaminated with F. tularensis bacteria. So if you get exposed, you will probably get sick, but there is a low probability for getting exposed.
  • incubation period – the time it takes to start having symptoms after you are exposed to an infectious disease. A longer incubation period increases the chances that someone will get exposed to a disease and travel home before getting sick. A shorter incubation period, like for influenza, means that a lot of people can get sick in a short amount of time.
  • contagious period- the time during which you can spread the illness to other people and may start before you have any symptoms
  • quarantine – used to separate people who have been exposed to a contagious disease and may become sick, but aren’t sick yet
  • isolation – used to separate people who are already sick with a contagious disease
  • transmission – how the disease spreads, including direct (direct contact or droplet spread) vs indirect transmission (airborne, vehicleborne, or vectorborne)
  • R0 (r nought) – the basic reproductive number or the number of new infections originating from a single infectious person among a total susceptible population
  • Rn – the net reproductive number, which takes into account the number of susceptibles in a community
  • infectious period – how long you are contagious

Got all that?

How Contagious Is Measles?

If not, understanding how easily you can get measles should help you understand all of these terms.

Measles is highly contagious, which is likely why all of the Brady kids got sick.
Measles is highly contagious, which is likely why all of the Brady kids got sick.

Measles is highly contagious, with a very high R0 number of 12 to 18.

That’s because:

  • the measles virus can live for up to two hours on surfaces and in the airspace where an infected person coughed or sneezed
  • infected people are contagious for up to four days before they have a rash and even know that they have measles, so expose lots of people even if they get put in isolation once they get diagnosed
  • infected people continue to be contagious for up to four days after the rash appears, so can continue to expose people if they aren’t put in isolation

So you don’t need to have someone with measles coughing in your face to get sick. If they coughed or sneezed at the grocery store, on the bus, or at your doctor’s office and then you entered the same area within two hours, then you could be exposed to the measles virus and could get sick.

Why don’t we see at least 12 to 18 people in each measles outbreak anymore?

That’s easy. The definition for R0 is for a total susceptible population. Most folks are vaccinated and protected, so even if they are around someone with measles, they typically won’t get sick.

Still, up to 90% of folks who aren’t immune and are exposed to measles will catch it. That includes infants too young to be vaccinated, kids too young to be fully vaccinated, and anyone who has a true medical exemption to getting vaccinated.

The measles has a very high R0 is easier to see when you compare it to those of some other diseases

 

Infection R0
Diphtheria 6-7
Ebola 1.5-2.5
Flu 1.4-4
MERS 2-8
Mumps 4.7
Pertussis 5-17
Polio 2-20
RSV 3
SARS 2-5
Smallpox 5-7
Varicella 8-10

Why such a big range for some diseases?

These are estimates and you are more or less contagious at different stages of each illness.

Fortunately, in most cases you can just get vaccinated and protected and don’t have to worry too much about them.

More on the Contagious Periods of Diseases