Yesterday Pfizer announced that its COVID-19 vaccine is more than 90% effective. While a 90% effective vaccine is more than what everyone expected, I find it concerning that the duration of immunity offered by the vaccine is not mentioned by Pfizer, or for that matter, any other vaccine manufacturer. I guess that’s because they themselves don’t know how long a person who has taken the vaccine will stay immune to COVID-19.
From what I understand, a vaccine isn’t a miracle drug that stays in the human body and fights the disease on its own. A vaccine is something that fools the human body into thinking that a virus has attacked the body. So the body starts creating anti-bodies to fight the virus. Later when the real virus actually attacks the body, the anti-bodies are ready to fight back and defeat the virus. If anti-bodies aren’t ready in large numbers then the virus can over run the body and cause serious damage or death. This is similar to a country having its army deployed on its border ready to fight a foreign invasion as opposed a country starting to recruit citizens to join the army after the enemy has already attacked.
Unfortunately, in the case of COVID-19, the anti-bodies get flushed out of the body over time. This causes people to get re-infected with COVID-19, sometimes even as soon as three months. Of course, the second time the body is better prepared to fight the virus due to the presence of memory T cells which will trigger a faster and stronger imune response. But if a person can get re-infected with COVID-19 then it follows that someone who has taken a vaccine can get COVID-19 after the anti-bodies that were created due to the vaccine get flushed out of their body. This is not a good situation.
Does this mean that all the 7+ billion people in the world will need to get vaccinated after every few months? We know that it’s going take a very long time to vaccinate everyone for the first time. The other day, AIIMS Delhi Director and member of India’s task force on COVID-19 management said that common people in India will need to wait till 2022 to get vaccinated. This is due to complexities of procuring the number of doses required for our huge population, not to mention the humongous public exercise of actually vaccinating every citizen. Now imagine vaccinating every Indian every few months, or maybe every year.
Most people I’ve been talking to seem to think that everything will return back to normal once the vaccine arrives. Will it really? I don’t think so. In time COVID-19 will cease to be a pandemic and will become an endemic disease instead. This means there will always be a baseline level of COVID-19 infection in the world. We will have to learn to live with it and manage the situation by taking vaccine shots at regular intervals. This will be the new normal.