As the Delta variant of SARS-COV-2 continues to sweep the globe, some countries are reportedly lifting pandemic restrictions, despite only moderate vaccination rates. The World Health Organization (WHO) has warned that Delta may be just the beginning of virus evolution, and a new modelling study suggests that high levels of viral transmission combined with moderate vaccination rates may be the ideal scenario for new variants to emerge.
In about six weeks, the Delta variant’s share of all COVID-19 cases in the United States rose from about 10 percent to a staggering 83 percent. The increasing dominance of the Delta strain in the US is not surprising, but its rapid spread has recently been “disturbing”, according to The director of the US Centers for Disease Control and Prevention (CDC), Rochelle Valensky.
Despite an increasing number of breakthrough COVID-19 infections being reported in vaccinated populations, the vaccine remains highly effective in preventing hospitalizations and deaths. Francis Collins, director of the US National Institutes of Health (NIH), says current vaccines can reduce the risk of severe COVID-19 and hospitalization by 25 times.
So, according to infectious disease expert Anthony Fauci, the vaccine is still effective, but not enough people are getting it yet. Currently, only about 50 percent of the U.S. population is fully vaccinated, and rates vary widely from state to state. States such as Alabama and Mississippi had only about 35% of their populations fully vaccinated, while Massachusetts, Connecticut and Maine were all vaccinated in the mid-1960s.
With restrictions like social distancing and wearing masks returning to some U.S. states, Fauci said he sees no need to block the current wave. But he noted that increasing vaccination rates is the only long-term solution.
At the same time, vaccination rates in poorer countries remain worryingly low due to uneven distribution, prompting the WHO to warn countries to start reducing restrictions.
“Delta is a warning: it’s a warning that the virus is evolving, but it’s also a call to action before more dangerous variants emerge,” said Michael Ryan, WHO’s director of emergencies. The virus becomes more adaptable, the virus becomes faster. The game plan is still in place, but we need to execute the game plan more effectively than ever.”
Ryan emphasizes that our 2020 prevention strategies — such as masks, social distancing, and avoiding crowded, unventilated indoor Spaces — still work for the Delta variant. They must continue alongside vaccination to reduce transmission and limit the emergence of new mutations.
A new study published in Scientific Reports modeled the likelihood of sarS-COV-2 vaccine resistant strains emerging. The study found that the best environment for this mutation to occur was when there were high levels of virus transmission in a moderately vaccinated population. These models suggest that the optimal vaccination rate for the emergence of dangerous new mutations would be around 60 per cent.
Peter English, former chairman of the British Medical Association’s committee on public health medicine, points out that modelling studies are always wise to be cautious. But he believes the new study is reliable and consistent with other studies.
English also says many parts of the world abandoned epidemic restrictions before more people were vaccinated, so the problem is really quite simple. More virus in the community means more vaccinated people will be infected, which means there is a greater chance that the vaccine will escape transmission of the mutant. Englishi was not involved in the study.
Nick Davies, an expert in mathematical modelling at the London School of Hygiene and Tropical Medicine, said the results made sense, despite many uncertainties in the modelling.
“Every country should do an own strength, as far as possible to avoid creating fertile ground for the virus to evolve, it is a consistent with public health and economic target basic goal, because they are involved in control,” said Davies, who was not involved in the new study, “but in the end, to escape the emergence of strains is a global problem, Not a national problem; Once a vaccine mutant appears in one place it becomes a problem for everyone.”
The new study does not advocate a lockdown in vaccinated populations, but suggests a series of non-drug measures that should be taken before transmission in specific communities is reduced. In addition to wearing masks and social distancing, the study recommends considering extensive testing and genomic surveillance and rigorous contact tracing to help isolate infected people and limit further transmission.
In the end, the researchers agreed with the STATEMENT issued by the WHO, reminding people that the only solution is to spread the vaccine evenly around the world. “Without global coordination, vaccine-resistant strains may be eliminated in some populations but persist in others. Therefore, a truly global vaccination effort may be necessary to reduce the chances of drug-resistant strains spreading globally.”