‘Next-gen’ COVID-19 vaccines may be needed to tackle emerging variants, say scientists

spre of COVID-19 variants is t an immediate problem but it’s time alrey for next-gen preventives to tackle m, say scientists as countries fine-tune ir vaccine dissemination programmes and race to put more vaccines in market gars pace.

Work on vaccines will have to continue on parallel tracks – one to tackle SARS-CoV-2 virus with first generation vaccines and or to prepare for possible mutations and new variants – say experts as y map future course of infection. Responding to concerns on effectiveness of current vaccines in face of emerging variants, immulogist Satyajit Rath said vaccine-resistant virus variants are eir t present or t spreing in sufficient scales and rates to be an immediate problem.

And though present vaccination campaign will indeed contribute to slowing pandemic, next-generation vaccines to deal with “most vaccine-resistant of emerging variant viruses will need to be developed from w even as we begin to vaccinate communities with first-generation vaccines”, scientist from New Delhi’s National Institute of Immulogy told PTI. An editorial in journal Virulence earlier this week ted that a threat to vaccine effectiveness comes from emerging strains, both existing such as ones reported from UK, South Africa and Brazil -- as well as those yet to come.

variants found so far have undergone changes or mutations that mean y can infect human cells more easily than original version of vel coronavirus that started pandemic. A recent study by researchers, including those from Rockefeller University in US, suggests that mRNA vaccines for COVID-19 may need to be updated periodically to avoid potential loss of clinical efficacy against newly arising variants.

study, posted on preprint repository BioRxiv, is yet to be peer-reviewed or published in a journal. An mRNA vaccine uses a syntic RNA (genetic material) encoded with instructions to make specific proteins of SARS-CoV-2 virus so body can generate an immune response without getting disease. In some good news, studies have suggested mRNA vaccines by Moderna and Pfizer appear to work against some of variants y were tested for.

A small study involving scientists from Moderna found US pharmaceutical company’s COVID-19 vaccine appears to work against new, more infectious variants of pandemic virus found in UK and South Africa. yet to be peer-reviewed study suggests that antibodies triggered by vaccine can recognise and fight new variants. Ar research released last week suggests Pfizer vaccine provides protection against UK variant.

According to experts, current COVID-19 vaccines are directed at spike protein of SARS-CoV-2 virus, and expect to trigger formation of antibodies that prevent spike protein of virus from sticking to human cells during infection. effectiveness of se vaccines is likely to be affected most by changes in cell-binding part of viral spike protein. According to immulogist Vineeta Bal, with time effectiveness of current vaccines will decrease as coronavirus will mutate even in future.

“A single new mutation in currently prevalent virus is unlikely to be sufficient,” Bal, from Indian Institute of Science Education and Research in Pune, told PTI.

virus, for its persistence, needs to maintain ability of receptor binding domain (RBD) of spike protein to bind to ACE2 receptor intact. angiotensin-converting enzyme 2, or ACE2 receptor, is  protein that provides entry point for coronavirus to hook into and infect a wide range of human cells. RBD is a key part of a virus located on its ‘spike’ domain that allows it to dock to body receptors to gain entry into cells and le to infection. Bal ted that in long run, vaccines may provide lesser protection due to evolution of virus.

“That is expected and is also a concern. More than vaccines, moclonal antibody rapy is likely to be versely affected,” said Bal. Moclonal antibodies are laboratory-me proteins that mimic immune system’s ability to fight off harmful antigens such as viruses.

“Moclonal antibodies bind to a very small portion of RBD and a mutation in that small portion can inhibit binding and hence utility of that moclonal antibody as rapy. “But vaccines are likely to trigger many antibodies which toger will cover a larger portion of RBD surface as compared to a moclonal antibody,” she explained.

re are currently two variants for which re are insightful data sets. One is British variant, B.1.1.7, and or is South African variant, B.1.351. Florian Krammer, a professor at Department of Microbiology, Icahn School of Medicine at Mount Sinai, said British variant may t have a significant impact on vaccine-generated immunity. “It does t look like B.1.1.7 will have a significant impact on vaccine-induced immunity. re might be some moclonal antibodies that may t bind/neutralise anymore, but post-vaccination serum seems to do just fine,” he wrote in a tweet.

“However, it is important that high antibody titers are induced and t all vaccine candidates do that. lower initial titers, higher impact of se variants might be and I do find that worrisome,” scientist ted.

  An antibody titer is level of antibodies in blood as determined by a test. Commenting on time it could take to modify vaccines to suit future variants, Rath said it could be much easier and quicker to come up with next-generation vaccine variants, since it took global community less than a year to come up with multiple vaccines to a new virus. Bal said this may be relatively easier for some vaccines such as ones based on viral mRNA than ors.

“ mRNA vaccines are possibly easiest to modify, but or vaccines such as evirus-based or protein subunit vaccines can also be modified. A regulatory process for fresh approval of se vaccines will have to be evolved,” she ded.

Although new variants are cause for concern, Rath said “ real practical question is, how much 'extra' protective capacity do vaccines generate, and does that 'extra' amount compensate reasonably for 'drop' in efficiency? It is this evidence that we should be looking for.”    “A major question that will arise and is t yet being asked is; how well will such a 'variant' vaccine work in an individual who has alrey been immunised with one of 'original' vaccines? pandemic is t done with us quite yet,” he ded. Covaxin, developed by Hyderab-based Bharat Biotech, is effective against UK variant of COVID-19, according to a study on 26 participants, shared by company on Wednesday. India has clocked more than 100 cases of UK variant.