To this date, five coronavirus variants of concerns have been identified which have posed serious threats to mankind. The most recent one among all the coronavirus variants is Omicron.
Only simple preventive measures like wearing masks, keeping hands sanitized can keep the virus at a distance. In addition to this, vaccination has also proven to be the most effective guard against the virus.
After two years dealing with the virus, a common question arises: Does Omicron infection make us immune to coronavirus invasion? Does it in any way improve our immunity?
“Immune system’s memory is one of its hallmarks”
“The human immune system’s ability to remember past infections is one of its hallmarks, but a durable response is not guaranteed. Some infections and immunizations elicit lifelong protection, but for others, the response is modest and requires regular reminders in the form of booster shots or new, reformulated vaccines,” says a Nature report.
Immunity of a body kicks in when a foreign pathogen enters the body. The B cells and T cells present in the body fight against the pathogen generating antibodies. These antibodies later remember the invader for sometime and act upon it when they attack.
Some of these antibodies also known as neutralizing antibodies bind to the pathogen and stop it from infecting other cells. Studies have said that the amount of neutralizing antibodies is dropping in people post COVID. “By September 2020, a handful of studies reported that neutralizing-antibody levels were dropping in people who had recovered from COVID-19. Some experts expressed alarm that immunity to SARS-CoV-2 might therefore be fleeting,” says the Nature report.
Vaccine and immunity
With five worrisome variants of virus spreading across the globe, and with only one sure-shot way to stop them, it is obvious to think that will this protect us forever? If not, then how long?
The purpose of vaccination is to induce memory of the virus within the immunity system and keep it ready for future attacks.
A December 2021 study says that vaccine effectiveness against symptomatic disease with the Omicron variant is significantly lower than with the Delta variant. It said that the protection provided by two doses of a messenger RNA vaccine drops to less than 40% just a few months after the second dose. But a third, ‘booster’ dose is helpful, it adds.
“Data from Israel, which had launched an aggressive vaccination campaign using the Pfizer–BioNTech mRNA vaccine, suggested that this vaccine’s protection against infection dropped from 95% to just 39% over the course of 5 months,” says the report.
Waning vaccine effectiveness was greater among older adults and among adults in clinical risk groups, says another study.
The way natural immunity works and the way vaccine induced immunity works is quite similar but scientists have found that the after second shot of vaccination antibodies peaked about a week and then declined for a couple of months. This explains breakthrough infections which were mostly seen in the third wave of the pandemic.
However, less hospitalisation during the third wave corroborates the fact that vaccines do not lose their ability to protect against the virus, though the effectiveness wanes to some extent.
Even when the antibody level is down, the B cells and T cells can still recognize the pathogen and induce immune response against it. Studies have also found that people who were infected with the delta variant of COVID had the same T cell response to Omicron, though the latter one was highly mutated.
Future variants vs vaccines
The need to develop a pan sarbecovirus vaccine has already been thought about, as the Chief Scientist of the World Health Organisation (WHO) Dr Soumya Swaminathan has said,”This is the time to invest in a pan coronavirus vaccine, but this will need global collaboration – on the science & the plans for equitable access. Researchers, companies, govt & multilateral agencies have a role to play.”
There is no stop to the growth of the virus and human beings should always be ready to fight against it.
WHO expert Maria Van Kerkhove says, “Omicron will not be the last variant that you will hear us discuss, and the possibility of future emergence of variants of concern is very real. And more variants that emerge, we don’t understand what those the properties of those variants may be,” and adds that, “certainly, they will be more transmissible because they will need to overtake variants that are currently circulating. They could become more or less severe, but they could also have properties of immune escape. So we want to reduce the risk of future emergence of variants of concern.”