Pros and cons of AstraZeneca vaccine in the spotlight

Claire Keeton Senior features writer
SA sold its stock of AstraZeneca vaccines to the African Union. File photo.
SA sold its stock of AstraZeneca vaccines to the African Union. File photo.
Image: Reuters/Dado Ruvic

Outgoing head of the Covid-19 ministerial advisory committee Prof Salim Abdool Karim  had favoured a stepped introduction of the AstraZeneca vaccine to SA until he found out the dosage interval had changed.

On Thursday, six eminent medical scientists slammed SA’s decision to resell its million doses of the AstraZeneca vaccine to the AU. “[This] squandered the opportunity to protect at least half a million of its most vulnerable citizens before the next resurgence” of Covid-19, they wrote in an editorial in the SA Medical Journal.

Karim told TimesLIVE this week: “I was part of the MAC [ministerial advisory committee]  on the AZ vaccine and I had recommended that AZ be considered as a secondary option. I had originally proposed that we should do a stepped introduction — give it to 100,000 people and see what it does.

“It is actually a very good idea and even the WHO was keen — but it turned out that it was not doable. AZ changed the dosing interval so while the initial interval was 28 days, they now say 80 to 120 days. This means that if you have such a long interval, we would have to vaccinate 100,000 people then wait three months and then give them another dose.

“I worked out we would only know the results in October or November but nobody will care about it by then. It was my whole proposal and it could have worked but with the change in dosage interval, I saw that it would not work.”

The SAMJ editorial warned that there were unlikely to be available alternatives to the AZ vaccine in SA in the next few months.

First author and infectious diseases specialist Professor Francois Venter, head of Ezintsha at Wits Health Sciences, and the co-authors wrote that the AZ vaccine’s diminished protection against mild to moderate Covid-19 caused by the variant was no reason to reject the vaccine — which had proven effective against severe disease caused by the original (ancestry) virus.

President of the SA Medical Research Council Prof Glenda Gray said of the AstraZeneca efficacy against severe Covid-19 caused by the variant: “This is a data free zone. We do not know yet if it will work or it will not work. There are compelling reasons to take a leap of faith, and compelling reasons not to.

“You have to have evidence and we do not yet have the evidence. We lack the evidence to forge ahead,” she said, adding there was no clear right and wrong position, just opinions at this time.

The AZ’s effectiveness against the variant in SA has not been proven but neither has it been proven for Pfizer, but SA has ordered 20 million doses of the more expensive Pfizer vaccine.

“SA’s muddled procurement strategy is further demonstrated by the commitment to buy 20 million doses of the Pfizer vaccine, for which there is no clinical evidence of efficacy against the B. 1.351 variant,” read the editorial.

“We agree with the decision to purchase the Pfizer vaccine, but the national department of health must concede that it then makes a mockery of the argument that we cannot use the AZ vaccine because of a lack of data against severe disease caused by this same B. 1.351 variant.”

“The Pfizer vaccine, like most other first-generation Covid-19 vaccines, is likely to confer high levels of protection against severe Covid-19, even caused by the B. 1.351 variant.”

Lab tests demonstrated a three-fold or more reduction of vaccine-induced neutralising antibodies by the Pfizer vaccine against the variant compared to the ancestry virus, the editorial noted.

The Novavax vaccine, which has not come up among the government’s choices, was proved to work against the variant, and the J&J vaccine being used to vaccinate health-care workers as part of the Sisonke implementation study.

“Intriguingly, SA has not included the Novavax vaccine as part of its rollout strategy, despite this being the only Covid-19 vaccine to report on efficacy [49-60%] against mild to moderate Covid-19 caused by the B. 1.351 variant, and 100% protection against severe Covid-19,” read the editorial.

“Unfortunately, none of the MAC-Vac’s advisories, rationales or decisions have been published in the public domain since January 3 2021, and none of the debate about specific vaccine choices has therefore been open to the public or the broader scientific community.” ​

TimesLIVE


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