Why is Zambia using a vaccine rejected by South Africa

Disclaimer: This question is not about safety of the vaccine. Benefits of vaccines may outweigh the risks . This question is about efficacy( It may be safe but is it effective?)

Background

On December 30 2020, the then Minister of Health Chitalu Chilufya announced an increase in Covid-19 cases that were linked to South Africa’s new variant 501Y.v2 or B.1.351 which was more contagious and had become dominant in may areas in the country.

This was confirmed by a CDC report that stated that the 16 fold increase in covid-19 cases in Zambia were due to the South African variant. The South African mutation was first detected in that country in October 2020.The South Africa mutation, known by scientists as B.1.351, was first detected in Zambia in December. The daily average of new cases rose from 44 in the first 10 days of that month to 700 in the first 10 days of January.


This means the dominant strain in Zambia from December was the South African variant.

Reaction to the Second Wave

Following South Africa’s devastating second wave, Health Minister Zweli Mkize announced that South Africa had secured 1.5-million doses of the Oxford/AstraZeneca COVID vaccine .This decision came amidst growing public pressure for South Africa to begin its national vaccine roll-out, ahead of vaccine doses secured through the international procurement mechanism, COVAX. At the time, a big factor considered by the health department was which companies could deliver doses immediately, given the limited stock availability due to high global demand for the jabs, Health Minister Zweli Mkhize said during a televised address.

Whilst in Zambia, Chief Spokesperson Dora Siliya announced that Government had approved Zambia’s participation in the free COVAX facility program to vaccinate 40% of the country’s population.

Efficacy of AstraZeneca against South african variantvac

However, after South Africa bought AstraZeneca vaccines from the Serum Institute of India, results from a small local study with only mild and moderate infections showed that the vaccine was not effective against the 501Y.V2 variant. The results from the study showed that AstraZeneca was only 21.9% effective against SARS-CoV-2 in South Africa.

When researchers isolated those cases of participants who were infected with the new variant of the virus (B.1.351 or 501Y.V2) they noted that the jab was only 10.4% effective. Further, laboratory studies confirmed that the variant was able to completely escape the vaccine’s immunity. Because of this the AstraZeneca rollout was halted.

South African experts, including the government’s ministerial advisory committee on vaccines, said the move to halt the roll out of the AstraZeneca vaccine was in line with South Africa’s evidence-based approach to COVID-19 decisions.

Dr. Benjamin Kagina, a senior research officer at Vaccines for Africa Initiative explained that the South African arm of the trial showed that AstraZeneca did not provide enough protection against mild to moderate COVID caused by the newly identified variant.

South Africa then decided to sell its stock of AstraZeneca doses on 15 March, a few weeks after a WHO expert group concluded that the “potential benefits [of the AstraZeneca vaccine] outweigh the known and potential risks”.

The WHO recommended the use of the vaccine even in countries such as South Africa where new variants are in circulation for which the jab had shown reduced efficacy.

“[The WHO] is simply saying go with it, because we think it’s still going to work. It’s a speculation,” explained Ministerial advisory committee for COVID vaccines, Barry Schoub. “There’s no evidence.”

In a Lancet publication entitled “COVID-19 vaccine efficacy and effectiveness—the elephant (not) in the room” , Olliaro,Torreel and Vaillant elucidate that it is important to know whether a vaccine with a given efficacy in a study population will have the same efficacy in another population with different levels of background risk of COVID-19. This is not a trivial question because transmission intensity varies between countries, affected by factors such as public health interventions and virus variants.

As part of the COVAX countries perhaps, Zambia did not have a choice in the say on the use of AstraZeneca vaccines for the pilot program. But as custodians of the health of Zambians, Government should explain which Evidence Based Data is being used to inoculate 40% of the population with a vaccine that is not efficacious according to South African studies where like Zambia the B.1.351 strain is dominant.