Why booster shots and vaccine mixing added to WHO concerns
Tedros Adhanom Ghebreyesus, head of the World Health Organization, has spoken out against countries buying booster doses of Covid-19 vaccines for their citizens when their less fortunate counterparts have yet to vaccinate workers essential and vulnerable populations. But as countries let their hands be guided by fear or despair, news has also emerged that Thailand decides to mix two types of vaccines as it finds itself caught amid an alarming increase in cases. . The United Nations health agency has also called for caution on this matter, although several tests have attempted to explore the benefits of “mixing and pairing” Covid vaccines.
Why are countries ordering boosters?
U.S. pharmaceutical giant Pfizer has said it will seek emergency clearance for a third follow-up dose of its two-dose Covid-19 mRNA, as it found that the immunity conferred by its vaccine wanes over time even in as long as newer variants may be better suited to dodge the antibodies created by the jab.
“The Pfizer vaccine is very active against the Delta variant,” said company chief scientist Mikael Dolsten. But he warned that six months later, “there is probably a risk of reinfection as the antibodies, as expected, are declining.” A point of reference would be the example of Israel. The country reported a decline in the effectiveness of the Pfizer vaccine and Dolsten blamed this on infections in people who had been vaccinated in January or February.
Reuters news agency said Israel’s health ministry reported that the vaccine’s effectiveness in preventing both infections and symptomatic illnesses fell to 64 percent in June. However, at the same time, the vaccine was 93 percent effective against hospitalizations and serious illness.
Even so, Israel does not appear to be taking any risks and has said it will start giving a third vaccine to people with weakened immune systems, although it is still not decided whether it will launch open boosters for it. entire population.
Health officials in the United States and the European Union, meanwhile, appear to be sure that a third shot is not needed at this time. The U.S. Medicines and Disease Watchdogs said in a joint statement that people who have received both doses of their Covid-19 vaccines do not need a booster at this time. The country used Pfizer-BioNTech and Moderna mRNA injections and the Johnson & Johnson single-dose viral vector vaccine.
The European Medicines Agency (EMA) also said it was still early to ask if more than the two injections were currently needed.
What is the status of immunization around the world?
In the midst of this booster injection debate, poorer countries have been left behind in the race for vaccine supplies. A duke university tracker says that “many countries in Latin America, Africa and Asia have still not been able to purchase enough vaccines to cover their populations” while noting that “by the end of the ‘By summer 2020, the UK, EU countries and Canada had purchased enough doses through pre-market commitments to cover more than their entire population.
Experts explain that manufacturing pressures mean earlier deals made by richer countries leave only a “small slice of the pie” for low- and middle-income countries and the COVAX partnership, which strives to ensure equitable distribution of vaccines.
According to the tracker, high- and upper-middle-income countries have so far purchased or reserved nearly 8.5 billion doses of Covid vaccine while lower-middle-income and low-income countries have managed to get their hands on just over 2 billion doses. Which means that the global vaccination process follows very different paths for rich countries and less wealthy countries. But as travel opens up and countries crave economic action, the existence of the virus anywhere will continue to threaten societies that have achieved full vaccination. This is what prompted experts to fight for more vaccine cooperation to beat the pandemic.
What did Thailand do?
From a peak of around 4,000 daily cases in April – a record for the country at the time – Thailand has seen the number of new daily cases rise to more than 8,000 now. The AFP news agency said the Southeast Asian kingdom “was struggling to contain its latest outbreak fueled by the highly contagious Delta variant, with cases and deaths skyrocketing and the healthcare system shattering. is stretched “.
Looking for solutions to stem the tide, the country’s health authorities decided to mix a first dose of the Sinovac vaccine made in China with a second dose of the same Oxford-AstraZeneca vaccine known in India as Covishield in an attempt to get a “booster” effect in six weeks instead of 12.
The plan to combine the Sinovac vaccine, which is an inactivated virus vaccine, with AstraZeneca, a viral vector vaccine, comes as health officials seek to reduce the time between doses. “We cannot wait 12 weeks (for a booster effect) in this epidemic where the disease is spreading rapidly,” said the country’s chief virologist, Yong Poovorawan.
What did the WHO say?
However, the WHO has warned against such measures with its chief scientist Soumya Swaminathan, calling any strategy not based on scientific evidence a “dangerous trend”. “We are in a bit of a no data and no evidence area when it comes to ‘mix-and-match’,” she said.
According to reports, Swaminathan’s concern stemmed mainly from a lack of data on the mix of the two vaccines in question. “There are studies going on; we have to wait for that and maybe it will be a very good approach, but at the moment we only have data on the Oxford AstraZeneca vaccine followed by Pfizer, ”said Swaminathan. There have been several studies on the combination of Oxford-AstraZeneca and Pfizer-BioNTech injections which have found that such a decision “triggers an immune response similar to – or even stronger than – two doses of either. vaccine”.
So, while there are arguments in favor of mixing vaccines, it is necessary to have solid data before adopting such a strategy. Additionally, injections should only be mixed on the advice of public health officials and individuals should not make such a decision on their own.
“Individuals shouldn’t decide for themselves, public health agencies can, based on the available data. Data from mix and match studies of different vaccines are pending – immunogenicity and safety both need to be assessed, ”Swaminathan said in a tweet on June 13.
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