A modeling study has warned that vaccine stockpiling by nations could strongly affect the global trajectory of COVID-19 case numbers, and increase the potential emergence of novel variants of the SARS-CoV-2 virus. The research, published Tuesday in the journal Science, explored the effects of different vaccine-sharing schemes on the global persistence of COVID-19 infections, as well as the possibility of developing new variants using mathematical models.
The researchers noted that allocation of COVID-19 preventives among countries has so far veered toward vaccine nationalism, with countries stockpiling vaccines for their citizens to prioritize access over equitable vaccine sharing.
Carolyn Wagner, co-first author of the study, said: “Some countries that have had severe COVID-19 outbreaks have received few vaccines, while many doses lasted in countries experiencing comparatively minor pandemic effects. either in terms of mortality or economic dislocation.” Professor at McGill University in Canada.
“As expected, we have seen a large reduction in the number of cases in many areas with high vaccine access, yet infections are rising again in areas with low availability,” said study co-first author Chadi Saad-Roy, US I am a graduate student at Princeton University. , added. The researchers estimated the incidence of COVID-19 cases under a range of assumptions related to the vaccine dosage regimen, vaccination rate, and immune response.
They did this in two model areas: one with high accessibility to vaccines – a high-access area (HAR) – and a low-access area (LAR). The model allowed pairing of regions, either through import of matter, or for the development of a novel variant in a single region.
The study found that increased vaccine-sharing resulted in a reduced number of cases in LAR. Study co-author Michael Mina, an assistant professor in the Harvard T.H. Chan School of Public Health, said: “Because it appears that vaccines are highly effective in reducing the clinical severity of infection, these reductions in the public health The effects are very important.” we.
Senior study author C Jessica Metcalf, a Princeton associate professor, noted that higher case numbers in the non-vaccinated population would be associated with a higher number of hospitalizations and a larger clinical burden than in the highly vaccinated population.
The authors also drew on the framework developed in their previous work to measure the potential for viral evolution under different vaccine sharing schemes.
In their model, repeat infection in individuals with partial immunity – either from an earlier infection or a vaccine – resulted in the development of novel variants.
Study senior author Brian Grenfell, an affiliated faculty member at Princeton’s High Meadows Environmental Institute (HMEI), said, “Overall, the models predict that with limited vaccine availability the number of cases of LAR continues to increase as a result of viral evolution. will result in a higher potential for
“The study strongly underscores how important rapid, equitable global vaccine delivery is,” Grenfell said.
The researchers note that in a scenario where secondary infection strongly contributes to viral development in previously infected individuals, uneven vaccine allocation appears to be particularly problematic.
He added that global vaccine coverage would reduce the clinical burden from new variants, as well as the likelihood of these variants emerging.
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