How effective are vaccines against Covid-19? Data from Israel, the country with the most advanced vaccination campaign in the world, shows that the vaccine is already having a real effect, with hospitalisation rates among vaccinated groups falling compared to those less likely to have been immunised.
Israel started vaccinating its population on 19 December and has rapidly outpaced the rest of the world. As of 15 February, some 40 per cent of Israelis have received at least one dose and 27 per cent are fully vaccinated. By comparison, the UK – which is the third-fastest vaccinating major country relative to population – has given one dose to a fifth of its population and fully vaccinated less than 1 per cent.
While very early evidence hints at a vaccine effect in the UK, it is helpful to study Israel because it has fully immunised such a high proportion of its elderly population: more than eight in ten over-70s and seven in ten of those between 60 and 69, according to data from the Israeli Ministry of Health. (Few Palestinians in the Palestinian territories occupied by Israel have been vaccinated, however.)
An analysis – not yet peer reviewed – published last week by researchers at the Weizmann Institute of Science, comparing hospitalisation rates for over-60s and under-60s reveals a clear “vaccine effect” in Israel’s data. Hospitalisations for the former group peaked in mid-January, around three weeks after Israel began its vaccination campaign, by which time a quarter of Israelis, mostly the elderly, had received at least one dose of the vaccine.
Ehud Grossman, a doctor at Sheba Medical Center, the largest hospital in Israel, told the New Statesman that the vaccine may also be protecting the 15 per cent or so of over-60s who have not been vaccinated, through decreasing transmission of the disease. Evidence from Israel suggests that vaccinated people have lower viral loads, and are therefore less likely to pass on Covid-19 to people who are not immunised.
“We are now seeing fewer patients over the age of 60 coming into the hospital,” Grossman added. “If [over-60s] are getting sick, their sickness is less severe. There is no question that the vaccine works.”
By contrast, hospitalisations of younger people have risen in recent weeks, suggesting they are not yet benefiting from any vaccine effect as fewer of them have been immunised.
Israel has so far mainly relied on the Pfizer vaccine, which delivers full immunity seven days after the second dose. However, on 8 January, shortly before Israelis were allowed the second dose of the vaccine, Israel went into a third lockdown – making it more difficult for scientists to determine exactly what the relative effect of vaccinations on hospitalisations was versus “non-pharmaceutical measures”, such as social distancing and stay-at-home orders.
There seems to be a genuine vaccine effect, however. The large decline in elderly hospitalisations relative to younger people was not seen during previous lockdowns.
The researchers also compared the level of hospitalisations in cities that were fast at vaccinating, to those that were slower. The results show exactly what we would expect if vaccinations were working correctly: that areas vaccinating more quickly saw a faster drop in elderly hospitalisations. If elderly hospitalisations were falling only because of the national lockdown, we would instead expect them to drop fairly evenly everywhere.
However, the findings do not necessarily mean that restrictions can be significantly loosened if only the elderly are vaccinated. As the New Statesman reported last month, the virus circulating among younger people will continue to put hospitals under pressure, even if those groups are at less risk than older people.
Indeed, Israel is still in a relatively strict lockdown, having only on 7 February ended a ban on people travelling more than a kilometre from home. The government envisages being able to open restaurants for all by early March, with larger events and hotels open to those carrying a “green pass” that proves their vaccination status.
According to Doctor Grossman, vaccination rates are now falling because some younger people see little benefit in getting vaccinated from a disease unlikely to seriously affect them. Current rates are now around 100,000 doses a day, compared to 180,000 in late January.
Taken as a whole, the data from Israel, though encouraging, shows that the path out of lockdown is still long.