It was not known how long the vaccine’s protection would last and whether it would outlast the three- to six-month protection the body gets after a Covid-19 infection.
That was because the FDA’s requirement at the Phase 3 clinical trials was only a two-month follow-up after completion of the full vaccination regime.
So, when the first real-world data (outside of clinical trials) came out from Israel, some doctors were thrilled.
The preliminary scientific results of the Pfizer-BioNTech Covid-19 vaccination programme in Israel, although not peer reviewed yet, look promising.
In the report “Estimating real-world Covid-19 vaccine effectiveness in Israel”, published in medRxiv dated Feb 11, author Dvir Aran said the vaccine has a high effectiveness of 66% to 85% in reducing SARS-CoV-2 positive cases, and over 90% in reducing severe cases which can result in hospitalisation and death.
Daily positive cases and hospitalisation data were taken from the Israeli health ministry’s Covid-19 public database for the study.
Between Dec 20 and Jan 31, as many as 3,082,190 individuals in Israel were given the first dose of the vaccine and 1,789,836 have already had their second dose, according to the report.
Of those vaccinated, 31,810 tested positive for SARS-CoV2, and 1,525 were hospitalised with severe or critical conditions or died.
That was after the first dose and at the beginning of a third wave, which saw positive cases and hospitalisations more than double. A strict lockdown was imposed on Jan 8.
There were again doubts about the vaccines but the number of cases had fallen by 66%, seven days after the second dose.
For people over 60, who comprise a major proportion of the severely ill cases, the analysis suggests a reduction of severe cases by about 60% after the first dose, and up to 94%, seven days after the second dose.
The Israeli government had been under pressure to manage the spike in Covid-19 cases when the third wave hit the country after mid-December. For a small country of nine million, Israel had more than 8,000 daily cases early this month.
Israeli Prime Minister Benjamin Netanyahu then struck a bargain with Pfizer’s CEO, reportedly paying Pfizer-BioNTech and Moderna top dollar to receive doses quickly amid a global shortage.
Israel, in turn, would serve as a “global model state for the rapid vaccination of an entire country” and will send Pfizer anonymised medical information about the effects of the vaccine on the population.
The results from the data, once reviewed by the medical community, may prove useful ahead of Israel’s elections this March.
While the data looks promising, there are still a couple of questions that warrant confirmation.
The preliminary report did not differentiate between the impact resulting from vaccination and that of the lockdown. To what extent did the lockdown affect the reduction in the number of cases and severity of cases? Or was it all the work of the vaccine?
According to an analysis by the journal Nature, separating the population-level effects of vaccines from the impacts of other public-health interventions, such as social distancing and lockdowns, will be tricky and requires a lot more data.
The analysis also noted that Covid-19 vaccines would not have an impact on viral spread so soon as herd immunity will have to be reached first.
Moreover, Raina MacIntyre, an epidemiologist at the University of New South Wales in Sydney, Australia, said that many other countries are using much lower-efficacy vaccines, which are unlikely to control infection.
The other issue is that no one knows yet how long the immunity to Covid-19 will last. Some reports say it lasts for up to six months while others say it could be longer.
Institute for Clinical Research director Dr Kalaiarasu M Peariasamy said some reports have argued that the vaccine’s effects could last a year.
A new study, published on Jan 6 in the journal Science, counter-argued that immune response to Covid-19 dropped at a drastic rate. It highlighted that the immune response does not rely solely on antibodies but the overall human immune response.
It reported that Covid-19 patients who recovered from the disease still had a robust immune response eight months after infection, which is likely to last for years.
Kalaiarasu explained that using blood samples from recovered patients, researchers found T cell numbers declined modestly and (the immune) memory can last longer, similarly for vaccines that induce memory cells after vaccination.
He gave an assurance that the massive government and private funding had sped up vaccine delivery and that no corners were cut. The vaccines, he said, were safe.
“Malaysians should get vaccinated and protect themselves and their loved ones,” he said.
At the very least, health director-general Dr Noor Hisham Abdullah said that, based on the current available data, those vaccinated are protected for three to six months.
With Malaysia receiving its first shipment of the Pfizer-BioNTech’s mRNA vaccines today, Israel’s vaccine preliminary results help clear the air about its effectiveness.
The vaccine may not be able to prevent transmissions immediately but is likely to prevent more hospitalisations and deaths.
It seems like face masks, hand sanitisers and social distancing are here to stay for the foreseeable future, at least.
Meanwhile, the health authorities need to expedite studies on repurposed drugs to assist patients’ recovery – and maybe find a cure — while we wait for vaccines to be rolled out and the impact to kick in.