Covid-19 has killed 480,000 people in the United States and 2.39 million worldwide, while infecting 27 million people in the United States and approximately 109 million people worldwide. Though at the moment, hospitalizations, deaths and new cases are fortunately dropping, it does not mean we are out of the woods just yet, especially with variants increasing in the U.S. Although masks and social distancing are effective in slowing the spread of the virus, vaccines are a more effective means of doing this and achieving herd immunity. Development of vaccines in the past took years but new technology has enabled pharmaceutical companies to develop several vaccines in record time. Currently the U.S. has issued EUA’s (emergency use authorization) for 2 vaccines, Moderna and Pfizer, which are mRNA vaccines. The Johnson & Johnson vaccine should have an EUA soon. The E.U. and U.K. have approved the AstraZeneca Vaccine which is effective in preventing illness but this has not yet been reviewed here in the U.S. Other companies such as Novovax are also working on similar vaccines.
It is important to remember that the vaccine studies leading to EUA did not study whether the vaccines prevented infection with Covid-19. The issue was to see how well the vaccines protected against mild, moderate and severe illness.
All Covid-19 vaccines aim to stimulate our own immune systems to recognize a specific protein on the Covid virus called the S (spike) protein. This is the protein that allows the virus to attach and infect the human cell. To be clear, the S protein is the part of the virus that allows it to attach to the human cells, but in and of itself, the S protein does not cause any illness or damage. By exposing the immune system to this protein, the vaccine primes the immune system to recognize this as foreign, and if and when a person is infected, the immune system is already set up to attack the virus.
The vaccine from Moderna and Pfizer are mRNA vaccines. Researchers were able to map the genetic code for the Covid-19 virus, specifically for the S protein. This code is then carried in the mRNA vaccine which then allows the S protein to be produced by our very own cells, but when exposed on cell surfaces it is recognized as foreign to our body and our immune system begins to produce antibodies to it. It is these antibodies and other parts of our immune system called T cells that then attack anything that has that S protein, in this case the Covid 19 virus. Because the Moderna and Pfizer vaccines are essentially cellular “engineers”, they can be edited fairly easily to respond to changes in the virus itself.
The vaccines produced by J&J and AstraZeneca use an adenovirus, like the one that causes the common cold, and have added the S protein to it, effectively turning these vaccines into trojan horses. This then sets up the immune system to respond to the Covid-19 virus, however it may make it more difficult to change the vaccine to effectively respond to new variants. This, in fact, is why South Africa has stopped using the AstraZeneca vaccine, because of the emergence of the South Africa variant and this vaccine’s low level of effectiveness against it.
Moderna and Pfizer vaccines are about 95% effective after 2 doses in preventing mild to moderate illness and virtually 100% effective in preventing severe illness. These require 2 shots and have to be stored under very specific cold conditions: Pfizer’s has to be stored at -70°C and Moderna’s at -20°C. The J&J vaccine has the advantage of being single dose and is much more easily stored than the 2 mRNA vaccines. Less advantageous is it appears to only be 66% effective in preventing mild to moderate illness but is 85% effective in preventing severe illness. The AstraZeneca vaccine, which is also a 2-shot vaccine, is about 70% effective in preventing illness. It is important to remember that the full effectiveness of the vaccines does not occur until about 2 weeks after the 2nd dose in the case of Moderna and Pfizer, and after the single dose of the J&J vaccine. None of these vaccines as is, however, have been shown to be very effective against the variants.
Unfortunately, RNA viruses like Covid-19 mutate readily. This is what we have seen now with the U.K. variant as well as the South Africa and Brazil variants. In fact, the U.K. variant is now projected to be the dominant form of the virus in the U.S. by sometime in March. This U.K. variant is not only more infectious and more easily spread but has recently been shown to cause more severe illness and result in a higher death rate than the original Covid-19 virus. The South Africa and Brazil variants, though not as prevalent, are also more infectious and likely cause more severe illness. These variants present a whole new challenge to vaccine management. All the vaccines are less effective against these variants, showing only 60% effectiveness.
The truth is, it’s not the vaccines it’s the vaccinations. It is only until we achieve herd immunity where approximately 70% of people are immune that we will get ahead of the virus. During that time, while we are waiting for herd immunity to occur, this virus has already showed that it can and will mutate. It might only be a matter of time before a mutation occurs that might render the virus resistant to current vaccines and post infectious immunity. Thus, the advantage to the mRNA vaccines is that they are already being re-engineered to more effectively prevent illness with the current variants. This might then be given as a booster to the current vaccines.
What is of paramount importance is to still practice social distancing and continue the use of masks. Because the vaccines have only been studied in preventing illness we still do not know if the vaccines prevent infection and whether a vaccinated person can still pass along an infection. Studies going forward will hopefully answer this question. It is important to remember that the pandemic will not end suddenly. We will most likely see cases decrease assuming the variants do not develop resistance to the current vaccines, and the Covid-19 virus will become endemic like the flu, possibly requiring yearly vaccinations.
- E. Steven Lenger M.D., Founder & Owner, MPC CONSULTANTS
Compliments of My Personal Care Consultants – a member of the EACCNY.