Pfizer Covid-19 vaccine for SA has ‘95% success rate’

The Pfizer Covid-19 vaccine, 325,000 doses of which landed in the country last week, offers 95% protection against hospitalisation and death, according to a big new study from Israel published in the Lancet medical journal recently.

The latest results are further evidence that the two Covid-19 vaccines to be rolled out to South Africans from May 17 — the Pfizer/BioNTech and Johnson & Johnson vaccines — offer real protection.

The J&J vaccine is the only Covid-19 vaccine tested in a big study, of 44,000 participants, against the B1.351 variant of Covid-19 dominant in SA. The vaccine was found to offer 64% protection against severe disease and death. It also has the advantage of being a single-dose vaccine.

Scientists, clinicians and health officials warned that Covid-19 cases were picking up in SA “after a lull”, and vaccinating at speed and scale was critical to control the third wave. Proffessor Glenda Gray, co-principal investigator of the Sisonke J&J implementation study which provides the shots,  said the J&J vaccine had been given to about 370,000 health workers in SA by Friday.

But vaccine hesitancy among health workers has gone up following a brief pause in the study in April to investigate extremely rare and unusual blood clots linked to the vaccinations — about one in a million.

“We have seen an increase in vaccine hesitancy. Before the pause we were inundated but it has affected our uptake. It impacted on confidence and there is a lot more hesitancy. Even though the vaccine is reactogenic and can cause side-effects, people will likely be much worse off if they get Covid,” said Gray,  who is the president of the SA Medical Research Council.

Gray said they were vaccinating about 10,000 to 15,000 people a day and were on track to finish the Sisonke vaccination of half a million health workers by the end of next week, after which the national programme will kick in to vaccinate the remaining 700,000.

In the real-world, observational study in Israel, where about 70% of the population older than 16 has been vaccinated, two doses of the Pfizer-BioNTech vaccine provided more than 95% protection against severe disease and death.

Before people got their second shot (this has been developed as a double-dose vaccine) the efficacy was lower at 58% protection against infection, 76% protection against hospitalisation and 77% against death.

A study involving 800 participants in SA who got the Pfizer vaccine showed that nobody who got the Pfizer vaccine got Covid-19, while nine people on the placebo did — six infected by the dominant variant.

In a real-world study in Qatar of more than 200,000 people, reported in the New England Medical Journal this week, scientists found the Pfizer vaccine was more than 95% effective at preventing severe, critical or fatal disease from any form of the coronavirus, including Covid-19 caused by the B.1.351 variant.

The effectiveness at preventing infection dropped to 72% from 75% against the variant common in SA. The Covid-19 vaccines in use globally — 1.23-billion people had been vaccinated worldwide by Friday, according to Bloomberg — run the risk of very rare and unusual blood clots.

“You have a greater chance of being struck by lightning — twice — than getting a blood clot from a Covid-19 vaccine,”  said Wits professor Barry Jacobson, president of the SA Society of Thrombosis and Hemostatis, at the time of the J&J pause mid-April.

The risk of developing these clots after getting vaccinated — with doses of the J&J, Oxford-AstraZeneca or the mRNA vaccines of Pfizer and Moderna — is much lower than the risk of clotting after being infected with Covid-19, a study by Oxford University in April found.

“The clotting disorder, which affects the brain, known as cerebral venous thrombosis, or CVT,  is about 100 times greater among people who get Covid-19 than normal. Among the health workers, a few individuals have had allergic reactions and been successfully treated and the symptoms of headaches and fatigue after getting a shot are common but mild,” said Gray.

Pfizer SA country manager,  Rhulani Nhlaniki said the vaccines’ arrival this week was a “momentous” occasion for the company and “a huge boost to the SA government’s efforts to roll out the Covid-19 vaccines to the SA people as quickly as possible”.

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