The promotion of a COVID vaccine as a cure to the pandemic may be as misguided as the early projections that herd immunity could be a panacea.
To date no vaccination, other than against smallpox, has prevented the existence of a deadly virus and some have even led to the propagation of new wild strains such as the oral Sabin vaccine for polio.
100 percent vaccination will never result in 100 percent COVID eradication
So, eradication cannot be the target of vaccination nor of herd immunity. What the vaccines do very effectively is to prevent severe infection, prevent a little transmission, prevent hospital admission, prevent intensive care admission, prevent intrahospital transmission and prevent death – and they are quite good at that.
Politicians and public health officials know this, yet they persist in promoting one panacea after another. The reasons are not hard to uncover.
As any vehicle driver knows, during a potential petrol shortage, fill up the gas tanks and keep them topped up – even if you aren’t doing much driving. Conversely, the role of governments and suppliers is to prevent panic buying.
It is no different with the COVID pandemic. First of all, top up your immunity with a vaccine and then hope the authorities can minimise potential and present COVID panic so you don’t have to keep engaging in panic and anxiety-driven activity.
However, that may never be enough for antipodeans who persist in believing the fallacy that the infection can be eradicated by closing borders.
The truth is that COVID infection cannot be completely eradicated. A proportion of infected patients, ranging from 2·5% to 28% in different studies, don’t maintain detectable antibodies nor COVID neutralising activity. Young adults who had a previous positive COVID test still had about one-fifth the risk of subsequent infection compared with seronegative individuals. Although antibodies induced by initial infection are largely protective, they do not guarantee effective SARS-CoV-2 neutralisation or immunity against subsequent infection.
In addition, the presence or absence of antibodies 28 days after the first vaccine dose is not synonymous with protection or absence of protection from COVID-19.
The real beneficial effects of a vaccine on a population can be observed only if the vaccine is efficacious in older adults and widespread distribution of the vaccine exists, including to people who are most susceptible to COVID-19. High coverage among these groups who are at high risk of severe COVID-19 would have the greatest protective effect against serious disease endpoints.
There is a light at the end of the tunnel that is not vaccine based. Studies of blood donors show that many of them have pre-existing T-cell immunity to SARS-CoV-2 from studies of blood taken either before the COVID-19 pandemic or more recently among those without infection. In other words, some immunity existed before COVID burst onto the global stage in the first quarter of 2020, some immunity arose during the epidemic, even before vaccines were developed, and additional immunity likely will continue to arise even if current vaccine levels do not increase.
This is not to say that everyone who can get vaccinated should not do so. Vaccination is essential to reduce the incidence and severity of COVID. It’s just to say that no one should think that even 100 percent vaccination will result in 100 percent COVID eradication – no matter what the elected and public health officials tell you.