India variant: Expert discusses vaccines that are 'effective'
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The government has been forced to revise its protocols for rolling out the coronavirus vaccines in response to an uptick of cases of the new Indian variant in England. So far, the variant has been detected across the North West and London. Bolton appears to be a hotspot, where cases are spreading in areas with lower vaccine uptake. To curb the outbreak, the government has floated the idea of shortening the time between the first and second dose of the coronavirus vaccines to those most vulnerable.
The race to beat the variant makes the rationale seem understandable but it could be counterintuitive.
That’s because a new study has found that older people who waited 11–12 weeks for their second jab had higher peak antibody levels than did those who waited only three weeks.
As the journal Nature reports, the study suggests that delaying the second dose of the Pfizer–BioNTech mRNA vaccine could boost antibody responses after the second inoculation more than threefold in those older than 80.
The finding implies that speeding up the time between the two doses could compromise some of the immune response in the cohort that needs it the most.
It is the first direct study of how such a delay affects coronavirus antibody levels, and could inform vaccine scheduling decisions in other countries, the authors said.
“This study further supports a growing body of evidence that the approach taken in the UK for delaying that second dose has really paid off,” Gayatri Amirthalingam, an epidemiologist at Public Health England in London and a co-author of the preprint, said during a press briefing.
The current crop of coronavirus vaccines distributed in the UK is given as a two-shot regimen.
The second dose can be offered anywhere between three to 12 weeks after having the first dose.
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The minimum gap of three weeks between the doses was informed by clinical trials of the three vaccines used in the United Kingdom, which generally featured a three to four-week gap between doses.
On 30 December, the United Kingdom broke with the ranks of other countries and announced that it would delay the second dose by up to 12 weeks after the first.
To determine whether the delay yielded results, Amirthalingam and her colleagues studied 175 vaccine recipients older than 80 who received their second dose of the Pfizer vaccine either three weeks or 11–12 weeks after the first dose.
The team measured recipients’ levels of antibodies against the SARS-CoV-2 (the virus that causes COVID-19) spike protein and assessed how immune cells called T cells, which can help to maintain antibody levels over time, responded to vaccination.
Peak antibody levels were 3.5 times higher in those who waited 12 weeks for their booster shot than were those in people who waited only three weeks.
Peak T-cell response was lower in those with the extended interval.
But this did not cause antibody levels to decline more quickly over the nine weeks after the booster shot.
The results are encouraging, but are specific to the Pfizer vaccine, which is not available in many low to middle income countries, noted Alejandro Cravioto, chair of the World Health Organization’s Strategic Advisory Group of Experts on Immunization.
Indian variant – latest
In addition to reducing the time between the two doses, extra doses of vaccines have been sent to areas seeing a surge in cases, with everyone living in multi-generational households from 18-year-olds to grandparents due to be eligible for a jab immediately.
Mr Johnson’s roadmap out of lockdown is now under threat, with a question now hanging over the full lifting of restrictions on 21 June.
Ministers have so far insisted the easing of coronavirus restrictions will go ahead as planned next Monday, however.
“The four tests have to be met for June 21,” vaccines minister Nadhim Zahawi said this morning.
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