A GROWING number of countries that have been depending on vaccines developed in China are losing faith that these alone can rein in the coronavirus as they face continued surges in infections and the spread of the more transmissible delta variant.
On 1 August, became the latest nation to approve the use of a different vaccine as a booster shot. It will administer the Oxford/AstraZeneca vaccine as a third dose to bolster immune protection for those who have already received two doses of the Sinovac or Sinopharm vaccines.
In the past month, Bahrain, Indonesia, Thailand, Uruguay and the United Arab Emirates have all begun mixing and matching vaccines in a tactic known as heterologous vaccination in the hope of improving protection and stemming transmission.
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Although China鈥檚 two leading vaccines have gained emergency approval from the World 91色情片 Organization, not much phase III trial data has been made public for either. The jabs from Sinopharm and Sinovac Biotech both use inactivated virus particles to provoke an immune response. This is a more traditional approach than the Moderna and Pfizer/BioNTech mRNA vaccines, but has yielded worse results.
Studies of the Sinovac vaccine have produced disparate findings. A study of healthcare workers in Brazil found in January that it was at preventing symptomatic cases of covid-19, well below the 94 per cent reported for the Moderna vaccine and 95 per cent for the Pfizer/BioNTech jab. , however, found that it was 65 per cent and 91 per cent effective, respectively.
The Sinopharm and Sinovac vaccines are a lifeline for many countries in Africa, Central and South America, and South-East Asia that have been beaten to supplies of other vaccines by richer nations. Together, the two vaccines are being used in more than 100 countries.
But there has been disappointment with the efficacy of these vaccines, which may be even lower against the delta variant. Figures on this are yet to be published, but in July, Israel鈥檚 health ministry reported that the efficacy of the Pfizer/BioNTech jab against delta infection , although other studies have shown better results.
鈥淚 would not be surprised if Sinopharm and Sinovac鈥檚 efficacy is as low as 30 per cent or even less against delta,鈥� says , a virologist at the University of Hong Kong.
Sinovac has since that a third dose of its vaccine be administered to boost protection, following a study which found that antibodies declined to below the level obtained from natural infection six months after a second dose.
Meanwhile, some countries in South-East Asia and Central and South America are continuing to face large outbreaks despite much of their population being double vaccinated. Chile locked down for over a month on 12 June to stem a deadly surge in cases, after having given both doses to 47.3 per cent of Chileans and a single dose to 61 per cent. Like Uruguay 鈥� also a regional leader in vaccination efforts that has faced large outbreaks 鈥� about three-quarters of shots administered there have been the Sinovac vaccine.
In Indonesia, where the delta variant is driving a record spike in deaths, 131 healthcare workers have died from covid-19 since June, according to the independent data group Lapor COVID-19. Most were vaccinated with the Sinovac shot. Indonesia is now rolling out Moderna shots to healthcare workers as a booster.
There are concerns that Chinese shots may be failing at home too. Outbreaks emerged in Guangzhou in June, and in late July in Nanjing. has been fully vaccinated. The country is using mRNA boosters.
However, the Chinese vaccines remain a crucial line of defence against the pandemic worldwide. They might not be as effective at reducing transmission, but the Chinese vaccines continue to prevent hospitalisation and death, says , a virologist at the FAMERP medical school in S茫o Jos茅 do Rio Preto, Brazil.
Covid-19 mortalities in Uruguay were reduced by with Sinovac vaccines. And in an experiment in Serrana, a city of 45,000 in Brazil, deaths when residents were inoculated with Sinovac.
鈥淲e need Chinese vaccines to keep saving lives,鈥� says Nogueira. Heterologous vaccination is likely to become the most effective solution, he says, but for now, Chinese vaccines are vital for countries like Brazil, where only 19 per of the population is fully vaccinated.
When the global dearth of vaccines turns into a glut, aspirations should be raised though, says Dong-Yan. 鈥淚f we actually want to bring an end to the pandemic, to offer better protection and eradicate the virus from the human population, then we need better vaccines,鈥� he says. 鈥淎nd the reality is we can do better. We already have better vaccines.鈥�
