Professor Stebbing in his daily update expands on this. He suggests that there are falls in cases across two out of the five European countries but also a continued increase in the number of sick patients in hospital in the United Kingdom, Italy and France.
This is even before a potential further rise in cases as people return from their holidays and children return to school. This is a scenario which has already been playing out in Scotland where schools have already been back a couple of weeks and cases are at record levels. He suggests that this could in turn lead to some pressures on health systems as we head into autumn in late September and into October.
He suggests that the virus was clearly completely novel to our immune systems, with entire populations having no baseline level of immunity to fight the virus, which has resulted in populations being so vulnerable.
He suggests that it is a matter of time before broad immunity is reached while the vaccines or virus infections work throughout the entire population. However, reviewing endemic coronaviruses, he feels that these are strong analogues to where the population will end up with COVID-19.
He suggests that the vast majority of the population has immunity to these viruses, mitigating their severity. These viruses do, however, continue to spread infect the population annually but at lower rates of hospitalisation/mortality versus the first wave of COVID-19.
Boosters increase the speed of the immune response, which is important in vulnerable/high risk populations and T-cell immunity likely provides strong protection long term from initial vaccination alone.
However, boosters increase neutralising antibodies which, though much shorter lived as they decline over time from the last dose, support a much faster initial immune response.
Long term he suggests once the pandemic has subsided and most of the population has some baseline immunity to COVID-19 either acquired through vaccines or infection, he thinks the case count and severity of cases will drop substantially along with the need for additional protection from boosters. However, high risk populations such as the elderly, the very young will require boosters as a relevant added level of protection.
However, he goes on to ask do we need boosters now? He believes that they are helpful in curbing transmission, which is relevant today due to the unvaccinated population.
He also thinks that curbing the transmission of the Delta variant, which is dangerous in the unvaccinated and high risk population, is important as the booster, given the lower level of immunity across the population in the face of the Delta variant, provides an added benefit.
He asked the question what is the goal of the vaccination? Is it to prevent infection even asymptomatic versus preventing symptomatic versus preventing serious/hospitalisations/mortality?
In terms of preventing serious/symptomatic cases he feels that with limited changes overall he believes immunity to one variant of COVID-19 is highly likely to drive immunity to other COVID-19 variants even if they are marginally less so.
Long term, because of baseline immunity from vaccination and COVID-19 prior infections in many, feels there would be a limited risk of a new variant causing major disruption after Delta with the exception of those who are unvaccinated.
He notes that in the United States, the unvaccinated comprise the vast majority of new cases COVID-19 and hospitalisation with the recent surge of the Delta variant.
However, he acknowledges that long term, one way or another, this segment of the United States population will develop immunity to COVID-19 but the mortality rate will be much lower from vaccination rather than infection.
Dr Paul Ettlinger
BM, DRCOG, FRCGP, FRIPH, DOccMed