The second dose conundrum

Could the government’s decision to delay the second shot of the Pfizer-BioNTech vaccine be a mistake which allows COVID-19 to continue to spread much more easily than if it had stuck to the original plan of giving two doses, three weeks apart?

This question is given added poignancy as a result of a study by Sheba Medical Center in Tel Aviv.

Researchers studied the level of immunoglobulin G (IgG) antibodies in the blood of 102 of the first 1,000 staff at the centre to be given both doses of the Pfizer-BioNTech vaccine.

While the first dose did produce antibodies, they discovered that levels of antibodies jumped by between six and 12-fold after the second dose.

After the second dose, they said, antibodies were higher than in people who had developed immunity by recovering from the virus itself.

The leader of the study, Gili Regev-Yohai, told reporters that the level of antibodies was such that it was likely those given second doses would not be capable of transmitting the virus to others. Only two of the 102 people tested failed to develop high levels of antibodies – one of whom had a suppressed immune system from another disease. The team has not yet published any results, and has not yet collected data on how long the high level of antibodies will last.

Pfizer has warned the UK government that its Phase 3 trials did not provide data for anything other than its recommended regimen of two doses, 21 days apart. The government argues that it can protect more people in a shorter time by delaying the second dose.

However, Israel’s COVID-19 tsar has suggested that the first Pfizer dose may be less effective than originally thought, which could potentially complicate the UK’s current strategy of delaying the second dose.

There seems to be some inconsistency in the government’s position as to when people will receive their second dose. Foreign secretary Dominic Raab failed to give any assurance when interviewed on Sunday, but vaccinations minister Nadhim Zahawi told LBC radio on Monday morning that everyone would receive their second dose within 12 weeks – which could be up to four times as long a gap as Pfizer recommends.

Israel has been greatly praised for the speed of its vaccination programme – partly made possible by a deal with Pfizer in which it agreed to supply data on the efficacy of the vaccine in return for preferential delivery of doses.

By the beginning of this week, 22 per cent of the population had received their first dose. So far, however, the vaccination programme has yet to result in a fall in new infections among the population as a whole.

Data released on Monday showed that 9.4 per cent of tests are coming back positive – the highest rate since October. This is in spite of the country being in lockdown.

Source: Ross Clark – The Spectator

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