It’s been understood for a very long time that acquired immunity – the immunity to a virus that we obtain from recovering after being infected with said virus – is often robust and long lasting.
Studies in regard to Covid-19 have also shown that this is the case in regard to the coronavirus.
A recent preprint in the scientific journal Cell found that a longitudinal analysis showed “durable and broad immune memory” after an infection with Covid-19 “with persisting antibody responses and memory B and T cells”. Moreover, they took aim at the “notion” that immunity conferred after recovery from Covid-19 might be short-lived, saying that the investigation showed the generation of long-lived plasma cells and “refute the current notion that these antibody responses to human coronaviruses are short lived.”
A review of studies of immunity after infection published in the Lancet this month found that reinfection with Covid-19 after recovery from previous infection was very low – with studies suggesting it at between 0 and 1%. After data from Israel, then one of the most vaccinated countries in the world was examined, Science reported in August that “never-infected” people who were vaccinated were “six to 13 times more likely to get infected than unvaccinated people who were previously infected with the coronavirus.”
While urging caution and emphasising that vaccines reduced the harm caused by the virus, including hospitalisations and deaths, Science reported that “in one analysis, comparing more than 32,000 people in the health system, the risk of developing symptomatic COVID-19 was 27 times higher among the vaccinated, and the risk of hospitalization eight times higher” in contrast to those who had natural immunity.
Now, it seems that NPHET might be acknowledging that Covid immunity after infection is permanent, at least according to scenarios modeled by the team tweeted by Professor Philip Nolan who has been the chair of NPHET’s Irish Epidemiological Modelling Advisory Group since March 2020.
In considering an optimistic scenario for Covid -19 Public Health Advice, the slide states that “infection-induced immunity is permanent”.
This seems to contradict the advice of HIQA and NPHET that “the period of presumptive Covid-19 immunity is nine months post-infection.” Currently Gov.ie advises that a Covid Recovery Cert is only valid for 6 months after infection.
Prof Nolan’s tweet does also bring some recent findings back into the spotlight.
Ireland, one of the most vaccinated countries in the world, also has one of the highest rates of Covid-19 infection. There has been some speculation that the reason other countries such as the UK and Sweden which previously had a high rate of infection but are not now seeing the same rise in cases might now be benefiting from natural immunity as well as vaccination.
In Ireland, a leading immunologist, Paul Moynagh, recently posited that Belmullet in Co Mayo may have gone from being ‘one of the most Covid-infected places in the State to the least’ was likely due to “significant levels of immunity from natural infection”.
Similarly, at the beginning of November a Waterford GP, who also strongly urged vaccination, said the city was enduring the worst level of Covid-19 in the country because low levels of previous infections meant “very few people in Waterford” would have “the natural immunity one would get from people having contracted Covid-19”. He added that this meant: “Therefore, it was fertile soil for Delta to spread once it arrives,” he told the Irish Times.
In October, an advisor to NPHET, Cathal Walsh, told the Business Post that ‘Ireland’s immunity to Covid-19 will naturally improve over time as younger people and unvaccinated adults boost their antibodies by virtue of catching the virus’.
It seems that the current limitations on Covid Recovery Certs need to be revisited. The public are not best served when the authorities ignore the science.