Understanding Immunity: Natural Infection VS Vaccine Derived Immunity

New Delhi: Ever since the Novel Coronavirus or SARS-CoV-2 has come into our lives, special attention is being given to ‘immunity’. It’s the immune system that fights the virus and protects one from getting the COVID-19 disease and if one catches the virus, the human body develops immunity against it. Explaining how the body develops immunity when it encounters a new virus like SARS-CoV-2, Dr Soumya Swaminathan, WHO’s Chief Scientist called the immune system “amazing, versatile and complex”. She added,

When the body is exposed to a new virus like the SARS-CoV-2 virus, which it’s never seen before, the immune system does get activated and there are many things which start happening. The first and the most rapid response is the production of antibodies. And this is also accompanied by messages that are being sent to other parts of the immune system so that the T-cells or the cell mediated immune response is also activated. And ultimately, what happens is that if the body’s immune response is strong, it’s able to overcome the virus and eliminate the infection.

Also Read: BA.2 Sub-Variant Of Omicron Is More Transmissible Than BA.1, But Not More Severe, Says WHO

The job of the immune system doesn’t end there. It also develops a memory response so that the next time the body is exposed to the same virus, it’s able to respond much more quickly because the memory cells, both memory B cells and T cells in the body are able to recognise and respond.

Antibodies are one part of the immune system, but it’s a much larger and much more complex system which keeps us healthy and, you know, gives us the ability to respond to a lot of infections, said Dr Swaminathan who was answering queries about immunity in the WHO’s explainer series, ‘Science In 5’.

SARS-CoV-2 was a new virus that means the human body did not have immunity to it. But almost two years into the COVID-19 pandemic, we have vaccines against the virus. Explaining how vaccines help to develop immunity, Dr Swaminathan said,

Vaccines work by mimicking the organism, the virus or the bacteria. And so, the spike protein of the SARS-CoV-2 virus is taken and made into a vaccine. Of course, we know there are different types of vaccines – mRNA, the virus vectored vaccines, inactivated, but they all do the same thing, and that’s present in a safe way the antigen of the SARS-CoV-2 to the body. And so, the immune response that’s generated is very similar to the immune response to a natural infection. But of course, vaccines are a safer way of stimulating the immune system.

Also Read: COVID-19: Here Are The COVID Free Countries In The World, As Per WHO

If both – natural infection and vaccines – generate immunity, then should one get vaccinated if they have been previously exposed to the virus? Answering the same, Dr Swaminathan said, the natural infection does stimulate the immune response and gives you some immunity, but it varies from person to person.

If you have had a very mild infection, the immune response may be actually quite low than those who have had a severe infection and we don’t know exactly how long it will last. In some people, it lasts a few months. In some people, it goes to a year. So, the advantage of getting vaccinated, even if you have had prior infection, is that you’re really boosting that immune system and ensuring that your immune system will have a good memory and response to the virus, she said.

Also Read: Coronavirus Vaccine Glossary: 15 Terms To Know About Vaccination

Dr Swaminathan suggests that hybrid immunity, which is both natural and vaccinated, is the best kind of immunity to have. But, having hybrid immunity doesn’t mean that one can let their guards down and give up on masking, social distancing, and hand hygiene. The reason is, we don’t know how long the natural immunity lasts and secondly, vaccines do prevent severe disease and hospitalisation but are not 100 per cent effective against infection. Also, one can be a carrier of the virus even after vaccination.

We have seen with the variants that are emerging and especially, with the latest Omicron variant of concern, that it was able to overcome the immunity and therefore, it was able to infect a lot of people who actually had the previous infection or who had been vaccinated. Luckily, because of their immunity, they didn’t get ill, but they still were infected. And that’s why it’s important to continue to mask and to continue to observe the other public health measures, particularly if there’s a lot of virus still circulating in your community, said Dr Swaminathan.

Also Read: Coronavirus Outbreak Explained: What Is T-Cell Immunity And How Does It Provide Defense Against COVID-19?

NDTV – Dettol have been working towards a clean and healthy India since 2014 via Banega Swachh India initiative, which is helmed by Campaign Ambassador Amitabh Bachchan. The campaign aims to highlight the inter-dependency of humans and the environment, and of humans on one another with the focus on One Health, One Planet, One Future – Leaving No One Behind. It stresses on the need to take care of, and consider, everyone’s health in India – especially vulnerable communities – the LGBTQ population, indigenous people, India’s different tribes, ethnic and linguistic minorities, people with disabilities, migrants, geographically remote populations, gender and sexual minorities. In wake of the current COVID-19 pandemic, the need for WASH (Water, Sanitation and Hygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign will continue to raise awareness on the same along with focussing on the importance of nutrition and healthcare for women and children, fight malnutrition, mental wellbeing, self care, science and health, adolescent health & gender awareness. Along with the health of people, the campaign has realised the need to also take care of the health of the eco-system. Our environment is fragile due to human activity,  that is not only over-exploiting available resources, but also generating immense pollution as a result of using and extracting those resources. The imbalance has also led to immense biodiversity loss that has caused one of the biggest threats to human survival – climate change. It has now been described as a “code red for humanity.” The campaign will continue to cover issues like air pollution, waste management, plastic ban, manual scavenging and sanitation workers and menstrual hygiene. Banega Swasth India will also be taking forward the dream of Swasth Bharat, the campaign feels that only a Swachh or clean India where toilets are used and open defecation free (ODF) status achieved as part of the Swachh Bharat Abhiyan launched by Prime Minister Narendra Modi in 2014, can eradicate diseases like diahorrea and the country can become a Swasth or healthy India.