Stick with AstraZeneca vaccine despite South Africa variant, Vietnam advised

They argue that the South African variant is rare in Vietnam, with just one imported case detected to date, and the vaccine is effective against the Wuhan strain and the U.K. variant that are found in greater numbers in the country.

The Covid-19 vaccine in question was developed by British-Swedish company AstraZeneca in collaboration with Oxford University. Britain approved the vaccine for emergency use in December 2020.

On February 7, South African health officials said they were pausing the country's rollout of AstraZeneca's coronavirus vaccine after a study showed it offered reduced protection from the Covid-19 variant first identified in the country, a CNN report said.

"I wouldn't be too worried at the moment about the AstraZeneca vaccine. We know that this vaccine is very effective against the U.K. variant and not so much against the South African variant," Professor Adrian Esterman, University of South Australia, Australia, told VnExpress International.

Esterman explained that the study mentioned by CNN is a small one, covering 2,000 young volunteers of around 30 years old. With half getting the placebo and the other half the AstraZeneca vaccine, researchers found the efficacy of the vaccine against the South African variant was only 25 percent against mild and moderate forms of the disease. However, they couldn't come to a conclusion about severe disease or death.

Esterman said scientists in South Africa and their partners will do a large-scale study with elderly people to see how effective the AstraZeneca vaccine is. It's likely that the South African government will continue to roll out vaccines because the country is in the middle of a bad epidemic of the virus, he said. Even if the AstraZeneca vaccine prevention was at 50 percent of severe disease and deaths, it would still help South Africa a lot. Other studies have shown that the vaccine is likely to get that level of effectiveness.

As far as Vietnam is concerned, Esterman said, the only real question is: how effective is the AstraZeneca vaccine against virus variants seen in the country.

"If, at the moment, either the original Wuhan virus is dominant in Vietnam, or it's the U.K. variant, the AstraZeneca vaccine could still be very effective," he said.

The AstraZeneca vaccine has the distinct advantages of being affordable and being easy to distribute. Also, the company has said it is currently working on a new, more widely effective version.

On February 1, AstraZeneca PLC signed a deal to supply Vietnam with 30 million doses in the first half of this year for domestic inoculation. In the same period, Vietnam would also receive around 4.886 million doses of AstraZeneca’s vaccine via the Covax program.

Professor Adam Finn, University of Bristol, U.K., said the AstraZeneca vaccine has been shown to be highly effective against the virus that originated in Wuhan and the U.K. variant. At this moment, the vaccine is one of several that looks to be very useful in terms of controlling the pandemic across the world, he said.

People are more concerned about the South African variant now. It has been seen in different places, but only in small numbers at this point. Finn and his colleagues in the U.K. were confident that the AstraZeneca vaccine, which is widely available globally, has an important role to play in global vaccination programs because it is priced low and can be stored and transported easily.

Finn agreed with Esterman that the scale of study done in South Africa was small. He said that while it doesn't show clear protection against mild disease in young adults, more information on its effectiveness in older people and people with more severe disease could be available in the near future.

Professor Stephen Evans, University of London, the U.K., affirmed that there is little doubt that the AstraZeneca vaccine is still effective against most of the variants of SARS-CoV-2, including the variant first found in the U.K. and now the dominant strain in the country. He guessed it may well have some efficacy against more severe forms of the disease with other variants even if it is reduced against milder ones.

Antecedent variants

Toan Ha, Assistant Professor at the University of Pittsburgh Graduate School of Public Health in the U.S., said the issue in South Africa is that the load of virus in the population has drifted to the new variant. Therefore, clinical studies from populations with only antecedent variants do not apply.

He believed that at present, with the original virus and a small number of cases with the U.K. variant in Vietnam, the AstraZeneca vaccine will work well and be effective in protecting the population. The U.K. variant, believed to be up to 70 percent more transmissible than ordinary strains, is deemed responsible for triggering outbreaks in the northern provinces of Quang Ninh and Hai Duong late last month.

Toan said Vietnam should work with international partners including WHO, UNICEF, UNFPA and other international and local NGOs to raise funds for accelerating the vaccination process and to advocate the inclusion of all eligible populations to receive the vaccines.

"We need to keep in mind that the more people in the community are vaccinated in a short period of time, the better the chances to slow down virus transmission," he said.

Vietnam should also note that clinical trials of the Johnson and Johnson single shot Janssen Covid-19 Vaccine have shown it can be more effective in preventing the spread of the South African variant.

Not a unique thing

Tram Anh Wartel with the International Vaccine Institute (IVI) in South Korea said the lower effectiveness seen in South Africa with the AstraZeneca vaccine was not a unique thing. For instance, she said, a similar trend has been seen with vaccines like the Novavax and J&J in the U.S.

The emergence of variants of SARS-CoV-2 serves as a powerful reminder that viruses by their nature mutate over time, and that the scientific and control response will need to adapt over time, she said.

From a vaccine development standpoint, there is indeed a need to invest in research and development and continue generating data from the front runner vaccines that have been approved for emergency use, she added.

In light of the additional data on circulating strains, it tells people that as long as the disease continues to circulate somewhere, there will always be the risk that new variants emerge that make existing vaccines less effective everywhere, she said.

Wartel said it would be useful to get the data on the South Africa strain detected in Vietnam as well as other strains including the original one in order to assess the short-term impact of the vaccination campaign in the country.

"The bottom line is to drive down the transmission everywhere by all means including safety measures and vaccination, and if we don’t, we will see (more) variants emerging," she said.

Esterman clarified that sometimes, the original virus, which people call a wild type, can almost disappear from many parts of the world because it gets taken over by a new variant.

Basically viruses mutate all the time. The new variants can completely overwhelm older variants, if they're stronger. That could have happened in many countries where the U.K. variant has become dominant.

He guessed that Covid-19 will probably end up like the influenza, when everyone will have to have a new vaccination every year, because the virus keeps changing.

He also said his expectations are high that Vietnam produces domestic vaccines at low cost and sells them the world over.

"It's good for the surrounding countries and I can't see why you can’t do it."