Smallpox, with 30 per cent mortality, was caused by two virus variants. Edward Jenner discovered that immunity to smallpox could be induced by inoculation with cowpox, a mild disease, and this served as a natural vaccine from the 19th century. From 1958 to 1977, the World Health Organisation (WHO) conducted a global vaccination campaign which made smallpox the only human disease to be eradicated.
One could argue that it took well over 100 years but most would agree that it took the better part of 20 years to eradicate smallpox, using a vaccine with 95 per cent efficacy, against a virus with only two variants, with cases easy to diagnose and isolate.
COVID-19 is a seasonal respiratory disease caused by the SARS-CoV-2 virus. With over 4,000 variants, it is now endemic in most countries around the world. Effective vaccines have been widely used and have drastically reduced the numbers of cases, hospitalisations and deaths.
Many cases manifest mild symptoms and diagnosis often depends on a polymerase chain reaction (PCR) test which can give very inaccurate results if not used judiciously. Studies have shown that the test may be up to 80 per cent accurate in people with symptoms but only in the first few days, accepting a result up to 24 cycles as positive.
Positive tests in asymptomatic individuals, or those unwell for eight days or more, or those positive only over 25 cycles (indicating a low viral load) have close to zero probability of confirmation by laboratory culture.
Asymptomatic PCR-positive cases rarely transmit infection and transmission is also unlikely if people are not in close proximity to an infected person in an enclosed, poorly ventilated space.
Face masks, mainly N95 or N99 masks, are only partially effective in preventing infection in a closed environment. Masks reduce droplet-based transmission but aerosol transmission continues unaffected. Although some systematic evidence reviews, including low-quality studies, have found positive effects, the most recent review in the Cochrane Database of Systematic Reviews found little or no difference to the outcome of influenza compared to not wearing a mask. Evidence on COVID-19 transmission is not available. In any case, efficacy in the open air is not supported by evidence.
Social distancing over one metre and personal hygiene measures may reduce transmission by 30 per cent. Studies of mobility measures (such as tracking mobile phones) show that people have voluntarily complied with such measures in many countries. However, a study by Chaudhry in July 2020 showed that rapid border closures, full lockdowns and widespread testing were not associated with any reduction in COVID-19 mortality.
COVID-19 is endemic in many countries and epidemics are to be expected every winter
A more detailed study by Bendavid and colleagues at the end of 2020 conclusively proved that the more restrictive lockdown measures (such as quarantine, school and business closures, and restrictions of mass events) were not associated with reductions in case numbers, although very small effects (less than 15 per cent) could not be excluded.
In fact, the general tendency was for more restrictive measures to paradoxically increase case numbers. The quarantine of infected persons with their families was associated with a seven per cent increase in case numbers in France, for example.
Considering the massive economic, social and psychological harms of these measures, it is difficult to understand how they can be justified beyond temporary, short-term application to slightly reduce case numbers when a healthcare system is overloaded. Such is the current WHO recommendation. The WHO policy document for the control of epidemic and pandemic influenza, published in 2019, also strongly recommended against the institution of contact tracing, quarantine of contacts or border closure and entry or exit screening, even with a severe pandemic.
The novel COVID-19 vaccines have proven to be amazingly effective, with two of them achieving over 90 per cent efficacy in preventing infection in randomised trials. The Pfizer vaccine achieved admirable results in reducing infections, hospitalisations and deaths in Israel. However, the vaccines are not fully approved and studies of efficacy and safety will only be completed in 2023.
Considering rare to uncommon adverse events and deaths, their administration should be guided by appropriate risk-benefit calculations. If they are to be highly recommended in the elderly and those at high risk, the WHO and many countries, including the UK, have either not recommended or precluded their use in children and young adults.
Cases of haemorrhage, thrombosis and neurological damage are reported and studies have found that some are likely more incident with the vaccine than with COVID-19 itself. As such, the Council of Europe recommendation that vaccination should be a free and informed choice, and should not be cause for discrimination, is justified.
Any measure of population (herd) immunity must consider immunity to COVID-19 derived from prior infection. Re-infection with SARS-CoV-2 is rare. Those retesting positive after past infection are likely due to a false positive test. Natural immunity involves the production of more types of antibodies and likely lasts longer (over one to two years) than vaccine-induced immunity. In fact, immunity to SARS-CoV (which shares 80 per cent genetic material with SARS-CoV-2) has been found to last 12 and 17 years in separate studies.
COVID-19 immunity can be measured with antibody and T-cell tests and the European Parliament has decided that a ‘vaccine pass’ should be issued to those who enjoy such immunity. Recent studies indicate that those naturally immune have less chance of transmitting the virus compared to those vaccinated, possibly due to superior neutralising IgA antibodies in nasal passages.
COVID-19 is endemic in many countries and epidemics are to be expected every winter. Case numbers out of season are not likely to predict surges in hospitalisations and deaths, especially with so many people vaccinated. The emergence of more infectious, but less lethal, variants has been associated with decreasing mortality rates and the infection fatality rate of COVID-19 is now just 0.15 per cent, or only five per 10,000 in those younger than 70.
The harms of unsustainable restrictive measures, the poor efficacy of masks and the rare, but significant, risks of vaccinating those at low risk preclude strategies based on eliminating the disease.
One hopes that the strategy to live with COVID-19 in the future addresses all available science and abandons extreme measures.
Jean Karl Soler, medical doctor and researcher