Schoub allays fears about vaccine red flags

It has been a week of high drama on the global COVID-19 vaccine stage as niggling concerns about both the Pfizer BioNTech and Johnson & Johnson vaccines have raised red flags for different reasons.

This week, Health Minister Dr Zweli Mkhize halted the Johnson & Johnson vaccine rollout after the United States Food and Drug Administration (FDA) made a similar decision. The FDA reported that six women had developed blood clots soon after getting the vaccine. More than six million Americans have so far received the Johnson & Johnson vaccine.

This is the second time South Africa has paused the rollout of a vaccine, causing concern among the community.

Pressing this pause button caused “quite a bit of confusion and even anxiety in the general public”, said Professor Barry Schoub, emeritus professor in virology at the University of the Witwatersrand and the former director of the National Institute for Communicable Diseases.

He explained that built into the regulatory requirements for the licensing of the rollout of a vaccine programme like this is a vigilant lookout for any signals potentially relating to safety.

The report from the US, which like South Africa is extensively rolling out the Johnson & Johnson vaccine, “constitutes one of these safety signals”, he said. “Even if the incidence of one in a million is extremely rare, nevertheless it does need to be investigated as part of the protocol in order to make absolutely sure that the vaccines do meet all safety standards.”

Schoub said it wasn’t a suspension of the rollout, but “merely a temporary pause for a few days at most”. During this time, investigations will be carried out to see if these reports carry any meaningful signal about safety. It was a routine response to a reported safety signal, as rare as it is.

Meanwhile, red flags were also raised when the results of an Israeli study found that the South African coronavirus variant was more adept at “breaking through” the Pfizer vaccine. Israeli scientists said more research was needed.

Israel predominantly used the Pfizer vaccine to vaccinate millions of citizens.

Schoub said the scientists had made interesting observations, but as the authors stated, they were preliminary, and they couldn’t draw any real conclusions from this study.

He explained that there were several important limitations to the observations. The sample size was small – “too small to derive any significant statistical meaningfulness”.

The “breakthroughs” occurred from two weeks after the second dose. “We know that the efficacy of the vaccine matures and starts being fully effective only from four weeks onwards,” Schoub said.

There was no mention of the clinical manifestations of the breakthroughs, he said.

“Were they symptomless, or only mild symptoms? The latter is important as it’s known that the Pfizer vaccine is a potent stimulator of the immune system and elicits very high levels of neutralising antibodies, so that even if there is a reduction of activity against the variant, adequate levels of neutralising antibodies still remain to prevent at least severe disease, even if mild disease isn’t prevented.”

He said if it didn’t regularly prevent mild illness, “this can be tolerated”, as we do anyway in the case of common colds and flus.

He assured that the scientific data did suggest that the Pfizer vaccine would be very effective in preventing at least severe disease and hospitalisation against the South African variant from four weeks after the second dose of the vaccine.

“Nevertheless, until the pandemic is brought under control, it’s mandatory that all infection-prevention precautions – the non-pharmaceutical interventions – are maintained,” he said.

Schoub said that he was sure that interesting data would be forthcoming from Israel, which is in a pivotal position to carry out these studies following its highly successful mass rollout supported by an excellent data monitoring resource.

Mkhize announced on 14 April that a batch of the Pfizer BioNTech vaccine will arrive in South Africa in May.