Are Boosters Prolonging the Pandemic?
Three in four health workers in Africa remain unvaccinated
President Biden announced the Federal Emergency Management Agency will create stand-up vaccination clinics across the United States to provide booster shots to those who have completed the standard two-shot regimen. The booster dramatically increases immune response for the Pfizer-BioNTech and Moderna vaccines.
“I’ll be deploying hundreds more vaccinators and more sites to help get the booster shots in people’s arms,” Biden said on Dec. 21. “Unfortunately, we still have tens of millions of people who are eligible for the booster shot who have not yet gotten it.”1
Meanwhile, Israel is deploying a second booster shot due to signs of waning immunity in its third dose. The nation’s Pandemic Response Team ruled medical workers and anyone older than age 60 years could receive a fourth shot of the Pfizer vaccine. The shot will be available four months after receiving the third dose.2
But some people have raised the question of whether booster shots are unethical from a global perspective, and even counterproductive to ending the pandemic because highly mutated variants will continue to arise in unvaccinated patients. One of the critics of booster programs is Tedros Adhanom Ghebreyesus, PhD, director general of the World Health Organization (WHO).
“Blanket booster programs are likely to prolong the pandemic, rather than ending it, by diverting supply to countries that already have high levels of vaccination coverage, giving the virus more opportunity to spread and mutate,” Tedros said in an address on Dec. 22. “It’s important to remember that the vast majority of hospitalizations and deaths are in unvaccinated people, not unboosted people.”3
Omicron Shows Mutation Threat
Around 3.5 million people died of SARS-CoV-2 in 2021, exceeding the deaths due to HIV, malaria, and tuberculosis combined in 2020. Globally, the pandemic virus is killing about 50,000 a week.
“It’s frankly difficult to understand how a year since the first vaccines were administered, three in four health workers in Africa remain unvaccinated,” Tedros said. “While some countries are now rolling out blanket booster programs, only half of WHO’s Member States have been able to reach the target of vaccinating 40% of their populations by the end of the year because of distortions in global supply.”
In this debate, omicron may be exhibit A. The new variant has mutated to move at unprecedented speed, incorporating prior effective mutations with others that have not been seen in any variant of SARS-CoV-2.
“Two factors of the mutations in omicron are concerning,” says Pei-Yong Shi, PhD, a distinguished professor of molecular biology at the University of Texas Medical Branch. “First is the sheer number — 30 to 40. It really depends on how you count them in the different isolates. The number [of mutations] is way larger than the previous variants, including delta, which has around the range of a dozen.”
The second concern is the nature of these individual mutations. “There are a lot of ‘old comers’ that have been analyzed in other variants,” Shi says. “Like the 484 mutation and the 501 mutation. We have done a lot of work on these, and they have clearly been shown to invade neutralizing antibody activities. The 501 mutation increases the spike protein binding affinity to the receptor human S2 [binding sites] by hundreds of folds. It is concerning that these old mutations are there, and then there are a lot of new ones, which we [have not seen]. That combination has a lot of scientific foundation to trigger concern.”
Infectious disease clinicians and researchers in South Africa warn the scarcity of COVID-19 vaccines on the continent and a large population of immune-compromised patients with HIV — 8 million of whom are not receiving antiretroviral treatment — sets the stage for continued mutation and global spread of SARS-CoV-2.4
The prevailing theory is omicron grew and mutated over months in an unvaccinated patient with uncontrolled AIDS in South Africa. Thus, the world’s failure globally to extinguish the AIDS pandemic — to leave it burning among the impoverished and untreated — now compounds the risk of another pandemic of a highly mutable virus.
“Immunocompromised people with COVID promote the mutation and amplification of the virus,” Shi says. “That is the opportunity for the virus to change — it is like some sort of incubator or a petri dish. The virus can grow easily without much pushback from immune protections.”
It would be of great global benefit if wealthier nations helped Africa prevent and treat COVID-19 and HIV simultaneously, the South African researchers emphasized. The priority in such an endeavor would be to “vaccinate Africa” for COVID-19.
“Over and above the ethical arguments to address vaccine nationalism and reduce deaths globally, the available data strongly indicate that vaccinating people in Africa will help to reduce transmission rates globally, limit the emergence of new variants, and accelerate global control of the pandemic,” the researchers concluded.
Notably, researchers have not definitively determined how the highly mutated omicron variant arose. Some hypothesize a reverse zoonosis — a reintroduction into an animal population, followed by a period of mutation, and then transmission back to humans. It contains some mutations Chinese scientists found are compatible with mice in a recently published paper that has not been peer reviewed.
“[M]utations in the omicron spike protein significantly overlapped with SARS-CoV-2 mutations known to promote adaptation to mouse hosts, particularly through enhanced spike protein binding affinity for the mouse cell entry receptor,” the researchers reported.5 “Collectively, our results suggest that the progenitor of omicron jumped from humans to mice, rapidly accumulated mutations conducive to infecting that host, then jumped back into humans, indicating an interspecies evolutionary trajectory for the omicron outbreak.”
REFERENCES
- The White House. Remarks by President Biden on the fight against COVID-19. Dec. 21, 2021.
- Tercatin R. Why did Israel’s COVID-19 team recommend a 4th vaccine? A member explains. Jerusalem Post. Dec. 23, 2021.
- World Health Organization. WHO Director-General’s opening remarks at the media briefing on COVID-19 22 December 2021.
- Msomi N, Lessells R, Mlisana K, de Oliviera T. Africa: Tackle HIV and COVID-19 together. Nature 2021;600:33-36.
- Wei C, Shan KJ, Wang W., et al. Evidence for a mouse origin of the SARS-CoV-2 Omicron variant. bioRxiv 2021;12.14.472632. doi: https://doi.org/10.1101/2021.12.14.472632. [Preprint].
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