- Current vaccines prompt the body to make effective antibodies: Study
- Individual immune responses can be risky dealing with Covid: Study
- T & B cells play an important role in immune responses against infections
Washington: Current COVID-19 vaccines prompt the body to make effective, long-lasting T cells against SARS-CoV-2 that can recognise variants of concern, including Omicron, and protect from severe disease, a study has found. The research, published in the journal Cell, also shows that fully vaccinated people have fewer memory B cells and neutralising antibodies against the Omicron variant. Both T and B cells play an important role in the immune response against an infection. Scientists at La Jolla Institute for Immunology (LJI) in the US tested four COVID-19 vaccines – Pfizer-BioNTech, Moderna, J&J/Janssen, and Novavax.
The vast majority of T cell responses are still effective against Omicron, said study co-leader Alessandro Sette, a professor at LJI.
These cells won’t stop you from getting infected, but in many cases they are likely to keep you from getting very ill, said co-author Shane Crotty, a professor at LJI.
This is true in all the type of vaccines studied, and up to six months after vaccination, said LJI instructor Alba Grifoni, who co-led the work. These data come from adults who were fully vaccinated, but not yet boosted. Without enough neutralising antibodies, Omicron is more likely to cause a breakthrough infection, the researchers said. Fewer memory B cells means the body will then be slower to churn out additional neutralising antibodies to fight the virus, they said.
Most of the neutralising antibodies, i.e., the antibodies that work well against SARS-CoV-2, bind to a region called the receptor binding domain, or RBD, said LJI instructor Camila Coelho, another co-first author of the study.
Our study revealed that the 15 mutations present in Omicron RBD can considerably reduce the binding capacity of memory B cells, compared to other SARS-CoV-2 variants such as Alpha, Beta and Delta, Coelho said.
The good news, the researchers said, is that neutralising antibodies and memory B cells are just two arms of the body’s adaptive immune response. In a person exposed to SARS-CoV-2, T cells do not prevent infection, they said. However, T cells patrol the body and destroy cells that are already infected, which prevents a virus from multiplying and causing severe disease, the researchers said. The team noted that the “second line of defence” from T cells helps explain why Omicron infections are less likely to lead to severe disease in fully vaccinated people. To know whether the vaccine-induced T cells were actually effective against variants such as Delta and Omicron, the scientists took a close look at how these cells responded to different viral “epitopes.” Every virus is made up of proteins that form a certain shape or architecture. A viral epitope is a specific landmark on this architecture that T cells have been trained to recognise.
The study shows that while the architecture of Omicron is different enough to evade some neutralising antibodies and memory B cells, memory T cells still do a good job of recognising their targets. Overall, at least 83 per cent of the CD4+ (helper) T cell responses and 85 per cent of the CD8+ T cell responses stayed the same, no matter the vaccine or the variant. The researchers noted that the memory B cells that do bind Omicron are likely to also contribute to protection against severe disease. However, they emphasised that no one should count on T cell protection alone. The study sheds light on immunity at the population level, but individual immune responses vary, and relying on one’s untested immune system to fight COVID is a roll of the dice, they added.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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.[corona_data_new]