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CFS and the COVID vaccines

Nicholas Bennett, MA(Cantab), MBBChir, PhD

Infectious Disease and Immunology Expert


Happy New Year to all our VCFS families! It has been quite the year…but we enter 2021 with a considerable amount of hope regarding COVID vaccinations. There are looking to be 3 major candidates, as predicted in my last update, so here are my thoughts and recommendations based on the data and information we have so far.


Both the Pfizer and Moderna vaccines are very similar – both are mRNA-based vaccines with very high efficacy, as measured by a 95% reduction in the risk of symptomatic COVID infection, and very good safety profiles. The Pfizer vaccine is available under an Emergency Use Authorization (EUA) for 16-year olds and older in a 2-dose series, 3 weeks apart. The Moderna vaccine is also under an EUA for 18 years and older in a 2-dose series 4 weeks apart. The side effects are also very similar between the two vaccines – currently the only one of any real concern is a rare allergic reaction thought to be due to one of the lipid ingredients (poly-ethyleneglycol or PEG). Anyone who needs an Epipen for such an allergy should hold on getting those vaccines until they can have a proper discussion with their doctor.


Because the mRNA vaccines work on the immune system like a real infection, but without actually putting anyone through the real infection, they have been shown to result in very good immune responses. One study showed that 4 months after vaccination, study participants had COVID antibody levels that were 10 times higher than at the peak from a natural infection. This is probably because not only is the vaccine engineered to induce a strong immune response, but actual COVID disease is immune suppressing, so it can’t be expected that the response would be optimal compared to a healthy individual. mRNA vaccines also induce cellular as well as antibody immunity, making them ideal for people with VCFS who may have impaired antibody production. Although it is very common for people with VCFS to have low T cells, cellular function is generally preserved and it is recommended that all routine immunizations are given. Sometimes live-viral vaccines like MMR are delayed until physicians are comfortable that the child won’t get a complication, but this is increasingly unusual as we learn how well people with VCFS do with vaccinations. In any case, the mRNA vaccines aren’t live viruses – so in a sense you get all the benefits without the associated risks. If anything, because most of the side effects from the mRNA vaccines are due to an immune response, it may be that people with VCFS experience fewer of them than other people!


The third major candidate is the Oxford/Astrazeneca vaccine, created using a modified chimp adenovirus with the same coronavirus gene in it as the mRNA vaccines mentioned above. In theory it should do just as well, but the data has been mixed and it has been less clear about how best to dose this vaccine. Nevertheless, it was recently approved for use in the UK as a 2-dose series, and could be as good as the mRNA options. Its main advantage is that it is cheaper and doesn’t require being frozen for storage. Although the virus is engineered to be safe in humans, I’m not aware of data in patients with immune deficiencies, and so given a choice I might recommend using either the Pfizer or Moderna vaccines in people with VCFS, but if this one is your only option I wouldn’t necessarily wait to get something else.


There are vaccines also available from Russia (Sputnik V) and China (Sinopharm) that have supposedly got effectiveness around 80-90%, but the raw data is not as available as the vaccines mentioned above. Sputnik V is a two-vector system using two different adenovirus vectors (the Oxford vaccine uses the same vector for both doses). Sinopharm is actually unusual among the COVID vaccines in that it is made using very traditional vaccine-production technology, where the virus is grown in the lab then inactivated. Such killed vaccines are usually very safe, but sometimes not as effective. Sputnik V and Sinopharm are available in parts of Asia, Africa, the Middle East and South America, but not Europe or the USA.


A few quick answers to some obvious questions about the vaccines.


Q: Is it recommended for people with VCFS to get a COVID vaccine?

A: Yes – and you may qualify for earlier access as an “at risk” individual with an immune deficiency.

Q: Is it safe for people with VCFS to get a COVID vaccine?

A: Most of the available vaccines appear to be very safe in general, and are likely safe in people with immune deficiencies – certainly safer than having COVID for real! I would preferentially recommend the mRNA-based vaccines at this time, but that may change.

Q: How long will immunity last?

A: We don’t know for sure, but early data is very encouraging and likely at least a year.

Q: Should I get the vaccine even if I’ve had COVID?

A: Probably, but talk to your individual doctor about the timing and need to get a COVID vaccine.

Q: Should I get a blood test afterwards to check if the vaccine worked?

A: Probably not. Not all blood tests for COVID antibodies will detect the vaccine titers, and none currently detect the T cell responses. In any case, low/absent titers wouldn’t lead to a recommendation to repeat the vaccinations.

Q: Can my child get the vaccine?

A: Currently the vaccines are approved in late teens and older – as more data comes in on safety and efficacy that will change, but right now we don’t even know for sure whether the dose should be the same in younger children. Please consider enrolling in a clinical trial if possible.

Q: Do I still have to wear a mask to avoid COVID after being immunized?

A: For now, yes. The vaccine protects against COVID disease but may not entirely stop the spread, so until case counts drop significantly most of us should still be practicing mask-wearing and social-distancing as required.

Q: When will COVID be over?

A: I do not know…but the sooner we get people immunized the faster that will happen!

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