2nd jab key against new variant: Data
NEW DELHI: The B.1.617.2 variant of the coronavirus, which is believed to have contributed to the devastating second wave of Covid-19 in India, does not render vaccines ineffective but it could require people to get both doses in order to be adequately protected against symptomatic disease.
The inference, based on preliminary data from infections among people in the UK, has implications for India’s vaccination drive, according to experts who said the country must now focus on expanding coverage and may need to reconsider its decision to increase the gap between shots.
Data from the UK, first reported by the Financial Times on Saturday, suggested a single dose may be significantly less effective against the new variant. “One dose offered 33 per cent protection against symptomatic infection from B.1.617.2, and 51 per cent against B.1.1.7,” said the report.
The difference in protection reduced to a mere 6 percentage point when people were vaccinated with both doses, the report added. The data was based on a pooled analysis of people who received the PfizerBioNTech and the Oxford-AstraZeneca vaccine in the UK.
When both doses were given, the vaccines appeared to offer 81% protection against the B.1.617.2 variant and 87% protection against B.1.1.7.
Experts said that though there is a drop, vaccines continue to protect against the B.1.617 variant. “In any case both shots are required for good and lasting immunity so the focus should continue to be that. The data so far shows reduced but sufficient protection against B.1.617,” said Shahid Jameel, virologist and director, Trivedi School of Bioscience, Ashoka University.
“The focus should be on vaccination at scale,” he added.
A second expert said the findings reinforce concerns around delayed intervals for second doses, a policy that India and the UK have followed.
“The UK vaccine dose delay policy is controversial and risky, and the Indian policy needs reconsidering. The protection conferred by a single dose is not going to be enough to stop the spread of B.1.617, particularly as the vaccines in use in India are not the strongest known. Even the mRNA vaccines struggle against the resistant variants when given only once,” said John P Moore, virologist and professor at Cornell University’s Weill Cornell Medicine.
On May 13, India announced that people on Covishield (the India-made version of the Oxford-AstraZeneca vaccine) need to wait 12-16 weeks for their second doses, citing real world data from UK that showed improved efficacy when the gap between shots was expanded. But on May 15, the UK itself reduced the gap from 12 weeks to 8 weeks and accelerated rollout to more groups, citing the B.1.617 variant. Jameel added that it might be too soon to determine if the extended dosing schedules pose a risk.
The B.1.617 is a variant with three sub-lineages – B.1.617.1, B.1.617.2 and B.1.617.3. Among these, whole genomic sequencing has shown that B.1.617.2 has grown rapidly in several parts of the world, including India, UK and US.
According to an updated analysis by outbreak.info of data on the global repository GISAID, 58% of the samples sequenced in India over the last 45 days are of this variant, which now appears to have become dominant after rising from relative obscurity in midMarch. Along with B.1.617.1, the B.1.617 lineage now accounts for 70% of the samples analysed in the last 45 days.
Moore added that the data from UK reinforce what has been observed in lab analysis. “I am not surprised by the reports from the UK. The B.1.617 variant is known to have a set of mutations associated with antibody resistance, and assays in a UK lab (Gupta in Cambridge) confirm that. It’s a set of mutations not any individual one that’s responsible,” he said.
In an interview to Global News, the CEO of BioNTech, Ugur Sahin said on May 20 that he expects the Pfizer-BioNTech mRNA vaccine have around 70-75% efficacy in preventing infection of the B.1.617 variants. While this is lower than the 95% protection from the variant that was first seen in Wuhan, experts said vaccines are likely to still offer significant protection from severe illness.