Immunity, vaccination and disease transmission

Okay, everyone. Cold and flu season is upon us, so it’s time to talk to you about immunity and disease transmission.

Herd immunity occurs when a large portion of the population is immune or less susceptible to a disease. It is mostly mediated by humoral immunity, when B cells have made antibodies and memory cells in response to an earlier infection.  Infectious diseases are transmitted from person to person, but when herd immunity is achieved, the chains of transmission are broken. This means that susceptible persons are much less likely to interact with infectious persons, thus reducing the risk of infection by those susceptible.

Practically speaking, herd immunity is achieved mostly by vaccination. The number I see most often to achieve herd immunity is 95%, meaning 95% of the population needs to be vaccinated in order to prevent widespread transmission of the disease. In reality, the requisite percentage is very specific to the disease and its natural history. For most diseases for which we vaccinate, 80-95% vaccination rate is needed to achieve herd immunity.

I’m going to tell you guys a secret now. A few months ago, someone was rolling out some unsubstantiated facts and figures on vaccination in my facebook group. I asked them to cite their source. Their response was to mock me and insist that it wasn’t worth it since I would never read them anyway. Being as I have feelings and go out of my way to be accepting even to lines of thought I do not personally endorse, I got pretty fucking mad. I don’t know what other people do when they get mad, but when I get mad, I learn everything I can about the subject in question. In this case, that included reading a vast amount of garbage and dangerous misinformation. I am talking 1-2 hours a day of reading articles and watching videos on completely inaccurate myths about vaccination.

So let me be really clear here: I read lots of posts and memes and even “scientific articles from medical doctors” supporting the anti-vaccination movement and I fervently, wholeheartedly, and without reservation of any kind, reject its merit. This information does not convey an accurate understanding of epidemiology, immunology or microbiology of infectious disease. I agree that, rarely, vaccine injury can occur. My niece had an ADEM reaction at the age of four which may or may not have been due to a vaccine (but probably not, because correlation does not equal causation.) I also agree that the risk of death or serious injury from illnesses for which we vaccinate is greater than the risk from vaccination.  I do not agree that any scientific link exists between vaccination and autism.

There is a very small portion of the population who have truly valid reasons for not vaccinating, and an even smaller portion who have truly valid reasons for completely not vaccinating. These include people with primary immunodeficiencies (for whom vaccination cannot be effective), those too young to be vaccinated, transplant recipients, and those with severe secondary immunodeficiencies (such as from medications.) Universally, these are also the people at highest risk from infection. These people cannot be vaccinated and are more likely to be killed by communicable diseases.

Mast cell patients are recommended to receive all vaccines per CDC (or relevant governmental body) guidelines. Premedicating with antihistamines is practiced by many mast cell patients prior to receiving vaccines. (Please note that steroids can interfere with vaccine action, and as such should be avoided if possible.) Simply having mast cell disease is not a contraindication to vaccination.


One of the best descriptions of how herd immunity works goes like this:

There is a population of 1,000,002 people. 1,000,000 are vaccinated for disease X and 2 are not.

An outbreak of disease X causes infections in 101 people. 100 are vaccinated and 1 is not vaccinated.

This means the rate of infection among the vaccinated population is 0.01% and the rate among the unvaccinated is 50%, 5000x higher.

A vaccinated person can still become infected, it is just less likely. They often experience less severe disease, but not always. It is also important to get boosters at appropriate intervals to maintain strong immunity.


Let’s address some specific cases.

Seasonal flu viruses are spread by droplets dispersed by coughing, sneezing or talking. Most often, the flu is spread when these droplets contact with the mouth or nose of another person. Less often, an uninfected person may become infected by touching a surface upon which droplets still rest and then touching their mouth, nose or eyes.

If you are infected, you can start infecting others more than a full day before you have any symptoms and for up to a week after. Young children and those with weakened immune systems can be contagious for even weeks longer.

For some, the flu is just a painful and unpleasant inconvenience, with no permanent damage to their health. However, for others, it can be disabling or fatal. In the 2012-2013 flu season, 171 children died from the flu. 50% of the children had no previous risk factors for complications. 90% of the children who died were not vaccinated.

In the 2010-2012 seasons, the risk of PICU admission for flu related illness was reduced by 74% through vaccination. The CDC estimates that 7.2 million flu related illnesses will be prevented by vaccination in the 2014-2015 flu season.


Measles is seeing a resurgence in the US, largely due to increased rates of vaccine refusal. Measles is still very common in other parts of the world. Prior to vaccination in the US, measles caused about 450 deaths a year. From 2000-2013, there were 37-220 cases annually in the US, with most being contracted by unvaccinated individuals outside of the country. This year, we have had a record 610 cases in 24 states, most as a result of 20 individual outbreaks.

Measles is unbelievably contagious. It has an R0 (pronounced “R naught”) of 12-18, which means that 12-18 other people can be infected by one person. 90% of the people close to a measles patient will contract it. An 83-94% vaccination rate is required for herd immunity against measles. It is transmitted by droplets as described above and can live on a surface for up to two hours. An infected person can infect others up to four days before they have a rash and up to four days after.

Measles is a very serious disease. It can cause a wide array of complications, including death. It can cause severe ear infections resulting in permanent deafness. Approximately 5% of children with measles get pneumonia, the most common complication resulting in death. It can also cause a fatal condition affecting the central nervous system 7-10 years after infection.


Pertussis, also known as whooping cough, has an R0 of 12-17. Almost everyone in the same house will be infected if not vaccinated. It is also spread by droplets and 92-94% herd immunity is required to be effective. A person can be contagious for up to three weeks before they have symptoms. Once the cough appears, they are most contagious, for up to 2-3 weeks after. After five days on antibiotics, a person is usually no longer contagious. A really important thing about pertussis is that the laboratory test used to detect it is not great. A negative test does NOT mean you don’t have pertussis, especially if you have been exposed.

Pertussis is especially dangerous for infants and young children, and can transmitted by holding infants too young to be vaccinated. 23% of infants under 1 year who get pertussis will develop pneumonia. 1.6% will die. People of any age can develop complications, including permanent loss of bladder control, rib fractures from severe coughing, and encephalopathy. Uncomplicated pertussis can cause severe coughing for up to 10 weeks.

In 2012, 48,277 cases of pertussis were reported in the US, but it has historically been underreported. 20 people died. This was the most cases in a year in the US since 1955.

I am going to California this February and I am literally terrified that I am going to get pertussis while I’m there and end up in the hospital. How unfortunate and unnecessary.

So how do you prevent getting sick and spreading illnesses?

  • Wash your hands often. Soap and water is best.
  • Regularly disinfect surfaces that might be contaminated.
  • Avoid close contact with sick people.
  • If you get sick, the CDC advises staying home for at least 24 hours after the fever is gone.
  • Cover your nose and mouth when you cough or sneeze.  Coughing or sneezing into your elbow is better than into your hand.
  • If you are sick, or have been exposed to someone who is, especially stay away from people at increased risk of danger from infection. This includes people with chronic diseases like mast cell disease. Infections are activating to mast cells. Furthermore, many of us have other health conditions and/or take medications that suppress our immune system. Patients with primary or secondary immunodeficiencies are at greatest risk. For these people, infection with even mundane diseases can be fatal.

All information on this topic is available at the CDC or WHO websites, with citations for corroborating peer reviewed literature on the applicable pages.

10 Responses

  1. Jan Hempstead December 22, 2014 / 7:58 am

    Thank you once again for your well researched post. I know that there is a large mast cell community that is very anti-immunization, but many years ago, I was sick with influenza. Not yet diagnosed with MCAS, I thought it was no big deal… a few days of rest, fluids and acetaminophen. WRONG! I was only 31 then and 2 weeks later, with still a raging fever, weakness like something I never felt, I landed in the ER. I now had bilateral pneumonia. It was so bad that I was admitted for several days for 2 IV antibiotics, nebulizers treatments around the clock and continuous oxygen.
    I will never forget the intensity of that sickness. And… I had seen a physician twice during the course of the flu! As you said, those tout no flu vaccine typically do not have science to back it up… real science.
    Thank you!!!

  2. Kelly December 22, 2014 / 8:46 am

    You just lost me as a supporter. My son has been recovering from severe vaccine injury. In the last year, he has developed mcad. There is not one shred of evidence showing safety and efficacy of multi-dose vials of vaccines; there are, however, over 100 showing their dangers to the mitochondria, the cns, the liver, etc. All of my friends have children who suffering from vaccine injury, and it really disappoints me to see you fall into the camp of the myth of herd immunity, as well as the false thinking that my child is now a sacrificial lamb for your imaginary greater good scenario. How dare you . Perhaps you need to check into the ingredients that are in each of these vaccines and tell your followers which ingredient is completely and unequivocally safe for injection.
    By the way, the illnesses you discuss are in the vaccinated population. I should know, my fully-vaccinated (and injured) son was quarantined for a week due to pertussis.
    Good luck in life.

    • Lisa Klimas December 22, 2014 / 9:24 am

      I have checked, thanks. I wasn’t lying when I said I have been researching this in detail for months. There have been many studies on vaccination.

      I stated that I do not argue there are vaccine injuries. I’m sincerely sorry to hear that your son was vaccine injured. As I mentioned, my niece had an ADEM reaction that may have been due to a vaccine. She had to learn how to read and write again, and has had significant neurologic and cognitive difficulties.

      I also stated that being vaccinated does not prevent disease, just the likelihood of it.

      Unfortunately, I expect I will receive many like comments due to the fact that I am trained in and therefore rely on peer reviewed science to inform my views on vaccination. However, I cannot ignore my own feelings and the multiple requests from parents of children with primary immunodeficiencies to write an article addressing disease tranmission and the grave dangers associated with it, and vaccination is part of that. I wish you and your son all the best.

      • Kelly December 22, 2014 / 12:04 pm

        Exactly, you are NOT trained, and you should not be telling others to get untested, unproven-for-safety multi-dose vaccines. I also rely on not only peer-reviewed, published bodies of work, but I rely on those bodies of work who have no conflicts of interest when it comes to their funding. I also have over ten years of research, schooling, and working with various physicians who have helped recover my child through biomedical intervention. I also believe that you should locate any information that you can as to the ingredients of each one of these vaccines that you are informing people to get for their children. How much aluminum do you consider safe for injection? What levels of bovine calf serum, monkey kidney cells, and human diploid (read: ABORTED FETAL STEM CELL) cells do you truly believe are safe? How much thimerosol? In telling people that they should get these vaccines, or get them for their children, because YOU said so (based on the biased publications that you read) – are you going to then be responsible for their vaccine injuries as well? Do you have time for that? “Well, I got these nine-at-once vaccines for my son because Lisa Klimas said to.” Let me know how that works out.
        PS – For every one of your biased, funded-by-pharma “vaccines are safe” abstracts, I can show you five (by NON-biased authors) showing their dangers to the human body.

        • Lisa Klimas December 22, 2014 / 1:41 pm

          I am trained as a scientist, and therefore in the interpretation of peer reviewed science. I didn’t tell anyone to get nine vaccines at once. I told people that I reviewed information and was unable to find convincing information to support not vaccinating. Any decision on vaccination should be discussed with the treating health care professional.

          Again, I have investigated what substances are found in the vaccines recommended by the CDC (and also the BCG vaccine not available in the US.) Stem cells are used in cultivation for vaccine development and preparation (as in other scientific purposes) but are not in the final vaccine. I find this piece of information to be an effective shibboleth for these sorts of conversations.

          I’m sorry that you’re not willing to engage in respectful discourse. I have received messages today from some other readers who asked for specific sources I had used for this post and who wanted to share some of their own. We discussed their experiences and mine. We did not talk to each other with hostility or disdain. I am always willing to learn more and if I find compelling evidence, to change my views. I got a recommendation for a well reviewed book supporting the counterpoint that I will be picking up in the next few days.

          I won’t be responding to this thread again. I wish you and your son all the best.

    • Lisa Klimas December 22, 2014 / 9:27 am

      I also really wish that people who choose not to vaccinate would offer up their sources in light of disagreement in case there is something I (and others) are missing. Unfortunately, the response I usually see/get is “You obviously don’t give a shit!” or “It’s not even worth it!” It’s unfortunate that I can’t lean on science without being vilified. In any case, that ship has sailed.

  3. Christen Farley December 22, 2014 / 12:26 pm


    Thank you for always presenting well researched information. It’s unfortunate you can’t post without such accusations. It’s unfortunate that there are rare instances where someone in vaccine injured. As a mother, my heart breaks for them. However that doesn’t mean the greater good of the population should stop vaccinating. It’s not a matter of opinions at this point, it’s science. It’s proven. I have 3 kids I vaccinate and 1 that I can’t. Just as anything in life there are risks. The incidence of vaccine injury (while tragic) are still VERY minimal in comparison to the risks of the majority of the population not vaccinating. I commend you for your continued efforts to educate people with researched information while keeping the sensitivity high on controversial subjects such as these.

  4. Yvonne December 26, 2014 / 12:16 pm

    Hi Lisa,

    My Mom had chronic heartburn for 30 years and probably aspirated during this time and ended up with systemic scleroderma and nearly died but was saved with a double lung transplant. She is strongly encouraged to take the flu shot every year. Some things that I would like to point out is that undetected mast cell activation probably caused the chronic heartburn. Another thing is that she ended up in hospital this fall only 12 hrs after getting the flu shot. Her stomach had filled up with mucous and fluid and aspirated and went to emergency because she couldn’t breathe. She was in hospital for a month because the drugs she was getting helped but also harmed This became obvious because the side effects she was experiencing were totally opposed to to purpose of the drug. Once the drug was stopped she got better. I can’t help but feel strongly that while yes it is very important to vaccinate to big illnesses. However I question the effectiveness of the flu vaccine and some sensitive people who are forgotten and fall in the cracks of the system “ie. Not able to get a mast cell activation diagnosis because the doctor is not going to help” might not benefit and may do harm. I think risk assessment (benefit vs. harm) has to be kept in mind.
    I myself got vaccinated for meningitis one year at the university as there was an outbreak. I thought it was a big illness and worth the risk. It knocked me out for 3 days ( I barely made it home) and the day after I got the shot they cancelled the vaccinations. Why? Did I get notification? No I heard about it after (when I got well). Something bad had happened and I have no clue what it was. It was really scary. They inject you (can’t take it back) and you’re left to deal with whatever happens.
    I’m left feeling a bit burned by these experiences and hesitant to get vaccinated again.
    Happy holidays,

    • Lisa Klimas December 27, 2014 / 5:42 am

      I understand feeling gunshy. I have been hesitant to share this story widely because I feel like it will be taken out of context to back a point I don’t support, but I feel it’s appropriate to share it here. In 2008, four years before I was diagnosed with masto, I received a pneumonia vaccine as part of my immunity testing. I had a very severe local reaction. My entire arm turned red and swelled. The pain was unbelievable. I needed weeks of steroids and my arm hurt for a couple of months. When it stopped hurting, I realized there was some type of structure under the skin. It grew larger in the following months and they eventually removed it surgically. The pathology report was wacky, with the final finding being unexplained fat necrosis. In retrospect, it was clearly a mast cell reaction.

      I have received subsequent vaccines with premedication without a problem. There was a bad flu outbreak here in the months before I was due to be inpatient for a week following my ostomy surgery, so I got the flu shot. No problem.

      The problem I have with anti-vaccination as a movement is that it is based largely in pseudoscience and in statistics that are applied out of context. It’s funny, one of the previous comments asks very pointedly how much fetal “calf” serum I was okay with being in vaccines. I actually laughed out loud when I read this. The reason for this is because fetal bovine serum (FBS) is used to enrich growth conditions for cell lines used to generate organisms for vaccine development. There is no FBS in the final vaccine. FBS is so ubiquitous that anyone with even a passing familiarity with vaccine development (or really, any type of cell biology) would know this. It is like, day one of microbiology, here is your FBS. It is that common. But it gets included in ingredient listing because it is a development product needed to grow cells to produce vaccine lines and people don’t understand. It’s hard to separate the legitimate concerns from the fearmongering.

      I’m not saying there are never side effects to vaccines, but as a society, we live largely free of a number of potentially fatal, very communicable diseases. The fact that we don’t die of polio as children allows us to live long enough to consider the long term effects of widespread vaccination.

      I strongly recommend all mast cell patients to discuss premedication for vaccines with their mast cell specialists. I understand there will be some that are unable to receive vaccines. I just want people to realize that simply having mast cell disease does not mean you cannot vaccinate. With the possibility that 5% of the population could have some level of MCAS, that could have really grave public health consequences.

      Thanks for your comment! I’m always happy to explain my thought process and I always appreciate your thoughts and insights.

      • Yvonne December 29, 2014 / 12:09 am

        thanks so much for your reply Lisa. As we have no access to a Mast cell expert (the doctor dropped us after the try pâtés test came back normal… And I thought we might get a standing order for another test when she was reacting) I am advising my Mom to premedicate with antihistamines before the flu shot next year. I just wish the doctors understood. But you understand. So thanks so much for being a kind ear we can talk to

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