Israeli Covid chief's claim single vaccine dose less effective 'inaccurate'

Israel’s health ministry has moved to row back on comments by the country’s coronavirus tsar, who suggested single doses of the Pfizer Covid-19 vaccine had not given as much protection against the disease as had been hoped.

The remarks by Nachman Ash, reported first in the Israeli media earlier this week, drew widespread attention for appearing to suggest that the vaccine was less effective than expected after a single dose had been administered as the country recorded record cases and extended its lockdown earlier this week.

As experts in the UK questioned whether it was too soon to make such a judgement, the Israeli health ministry pushed back, saying that the comments were inaccurate and had been taken out of context.

Israel, whose rate and proportion of vaccinations has put it at the front of global efforts, has been watched intently by other countries to understand the point at which its vaccination campaigns against Covid-19 are expected to bite and whether an initial single-dose regime is sufficiently effective.

So far more than 2.4 million Israelis – just under a third of the population – have received the first dose of the coronavirus vaccine and about 800,000 have received the second booster shot.

The issue of some vaccines being less effective after a single dose rather than two is well known, as well as the fact that protection is not immediate. While the first dose can take several weeks to promote an effective antibody response, the second dose can trigger different responses, supercharging the protection.

Pfizer itself says a single dose of its vaccine is about 52% effective. Some countries such as the UK have delayed administering their second doses to try to maximise the number of people given a first dose.

In remarks reported by Army Radio, Ash had said a single dose appeared “less effective than we had thought”, and also lower than Pfizer had suggested.

Addressing Ash’s quotes, the Israeli Ministry of Health said that the “full protective impact of the vaccine” had not yet been seen.

“The comments of the Israeli Covid-19 commissioner regarding the effect of the first dose of the vaccine were out of context and, therefore, inaccurate,” the spokesperson said.

Among those who had questioned Ash’s remarks was Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, who said it was too early to draw any judgements over delaying second doses of vaccine in favour of as wide a coverage with first doses as possible.

“It is vital that advice and policy take into account the latest available data. However, the reports that have come from Israel are insufficient to provide any evidence that the current UK policy in regard to delaying the second dose of vaccines is in any way incorrect.

“The reported efficacy of one dose has not been compared using the same methods and patients with the efficacy of two doses.”

He added: “The UK will soon have its own data showing efficacy after the first dose for the different vaccines currently in use and any policy changes should await more robust data. If, for example, the efficacy after one dose was 33% but the efficacy after two doses was 60%, the UK policy would still be justified.”

After recording its highest level of new infections since the pandemic began at the beginning of the week, Israel has reported a slow decline in cases, with the positivity rate declining from over 10% at the beginning of the week to around 9% by Thursday, with the government also suggesting the reproduction R number had fallen below 1 again.

Experts point to a lag in developing sufficient antibodies against coronavirus following vaccination of around a fortnight, with antibodies boosted significantly by a second dose.

The political spotlight has, however, remained focused on Israel’s ultra-Orthodox community, and lax enforcement of lockdown rules by police among the ultra-Orthodox, who have been blamed for bucking social distancing requirements.

On Thursday, the Ynet news website reported that several leaders in Jerusalem’s ultra-Orthodox Mea Shearim community have threatened to urge their followers to riot if police attempt to enforce the coronavirus closure restrictions in the neighbourhood.

Also on Thursday, in Bnei Brak dozens of ultra-Orthodox people surrounded and attacked a police vehicle enforcing the coronavirus lockdown in the city.