Vaccine makers in India and China are investigating whether their recently approved COVID-19 vaccines are effective against a fast-spreading variant of SARS-CoV-2 now circulating around the world. The move follows similar investigations by the makers of other leading vaccines.
Covaxin, developed by the Indian Council of Medical Research (ICMR) in New Delhi and Bharat Biotech in Hyderabad, is one of several first-rollout vaccines to use an inactivated whole virus to elicit an immune response. Three other inactivated SARS-CoV-2 shots have been approved or granted emergency use in China.
Researchers in India have theorized that such whole-virus vaccines could perform better against new variants than can vaccines that rely on the virus’s spike protein, such as those made by Pfizer and BioNtech, Moderna, and the University of Oxford and AstraZeneca.
If a variant escapes the immune response directed against the spike protein, a whole-virus vaccine could mean that other vulnerable areas of the virus can be attacked, says Srinath Reddy, an epidemiologist and head of the Public Health Foundation of India in New Delhi. “That is still on theoretical grounds,” he says. “Nothing has been demonstrated as yet.”
The Indian government cited this theory when it granted Covaxin emergency-use approval on 3 January, even though phase III safety and efficacy clinical trials have not been completed. “This approval ensures India has an additional vaccine shield in its arsenal esp against potential mutant strains in a dynamic pandemic situation — A strategic decision for our vaccine security,” tweeted India’s health minister, Harsh Vardhan.
ICMR virologist Nivedita Gupta says that council scientists are testing whether antibodies found in the blood of people vaccinated with Covaxin are effective at blocking a variant that emerged in the United Kingdom, called B.1.1.7, which is now circulating in India, too. The results are expected later this month, she says.
Two research teams in China have tested whether a specific mutation in the B.1.1.7’s spike protein could compromise the inactivated vaccine developed by Sinopharm, a state-run pharmaceutical company, according to Chinese state media. They report that antibodies produced by vaccinated monkeys and people can neutralize the variant, and the results have been submitted for publication. The company has yet to release detailed efficacy data from clinical trials of the vaccine.
Both Pfizer and Moderna, which are based in the United States, have said they are testing mutations in the B.1.1.7 variant and in one that originated in South Africa, called 501Y.V2, to see whether they weaken the performance of their vaccines. A preprint published on 7 January found that a mutation known as N501Y, which has been identified in both variants, did not alter the activity of antibodies produced by people who had been vaccinated with the Pfizer–BioNtech jab1. Data on other mutations and vaccines are expected soon.
But scientists have also noted that laboratory measurements of antibody activity are not always indicative of real-world vaccine performance.
Like many countries, India is using genomic surveillance to track variants of the virus as they emerge. Scientists at the National Institute of Virology in Pune, a biosafety level-4 facility, are sequencing SARS-CoV-2 samples from 30 labs across the country each month. They have isolated and cultured many variants, including B.1.1.7, which is present in India.
“Once you have a virus isolate, it gives you an array of opportunities in terms of tweaking your vaccines, making new diagnostic tests, understanding the effect of existing vaccines on the variants strains,” Gupta says.
After testing Covaxin against the B.1.1.7 variant, the ICMR will move on to investigating the vaccine made by the UK-based University of Oxford and AstraZeneca, which is being produced in India by the Serum Institute of India in Pune, and a second, unapproved shot made by Zydus Cadila in Ahmedabad, Gupta says.
Xie, X. et al. Preprint at bioRxiv https://doi.org/10.1101/2021.01.07.425740 (2021).