Covid-19 cases in England are on the rise, and people are reporting that they have caught Sars-CoV-2 for the second or third time.
A new analysis suggests that people who are not vaccinated should expect to be re-infected with Covid-19 approximately every 16 months.
Scientists warn that reinfections can increase the NHS's burden as winter approaches. Some are calling for the vaccination program to be extended to all students, including two doses for teens, and to include more teenagers.
Stephen Griffin, an associate professor of virology at Leeds University, stated that if you have high levels of prevalence and are exposed to the virus frequently, you will see more people get reinfected even though they were double vaccinated.
Last year, it was assumed that reinfections were possible, but this was very rare, with just two or three cases worldwide.
Now we know that natural immunity against Sars-CoV-2 decreases over time. A Danish study found that under-65s were protected for up to 80% for at least six month, while over-65s only had 47% protection.
The situation has been further complicated by the arrival of the Delta variant.
According to Danny Altmann, professor at Imperial College London of immunology, certain healthcare workers have moderately high levels of antibodies. These people have had symptomatic infections and were previously infected.
It is much more common than we used to seeing numbers before.
According to ONS data, published 6 October, 296 of the 20,262 Britons who tested positive in Covid-19 between September 2021 and July 2020 were found to have reinfected. This is defined as a second positive test within 120 days or more from an initial positive test. The median (median) time between positive tests was 203 days.
The reinfection risk seems to be higher than it was in May 2021, when Delta assumed the dominant variant.
Additional data from the USA, where several states have started reporting and tracking reinfection rates, supports that there is a significantly higher risk of getting re-infected with Delta.
Oklahoma has an estimated population of 3.9 million people. In September, 5,229 reinfections were reported. This is equivalent to 1,152 reinfections per 100,000. Reinfections have increased 350% since May.
The US Centres for Disease Control and Prevention defines reinfection as a laboratory-confirmed Covid-19 case that occurs 90 days or longer after a previously confirmed case.
Dr Nisreen Awan, an associate professor in public and health at the University of Southampton said: Given the rising incidence of Sars-CoV-2 infection in the UK, many of our students are aware of people who have been infected again, often after a short time.
Although we don't know much about reinfection risk factors, the assumption that all young people will get it is increasingly unlikely.
Professor Jeffrey Townsend, Yale University School of Medicine, and his colleagues analysed immunological and reinfection data from coronaviruses other than those that cause Sars, MERS, and common colds to answer this question.
Combining this data with other immunological data, including antibody, from patients who had recovered from SarsCoV-2, they were capable of modeling the risk of Covid-19 reinfection over the course time.
The Lancet Microbe published the research. It suggested that reinfections could become more common as immunity decreases, especially when there was a high number of infections.
Townsend stated that if there were no infection controls, no one was concealing or social distancing and no vaccines, then we should expect reinfection every three to five years. This means that an average person should expect to contract Covid every three to five years.
Vaccinations are suppressing infections but the UK reported 49156 Covid cases Monday, the highest number since mid-July. Secondary schoolchildren are at the highest risk, with 8.1% of them having contracted Covid-19 during the week that ended 9 October.
Townsend said that if you allow it run amok in any age group, it will be amok across all age groups.
These are the main implications. If you haven't been vaccinated yet, get it done. If you have been infected, get vaccinated anyway to prolong your protection.
Griffin stated that if you don't reduce the prevalence of infections in schoolchildren, you will see an increase in infection and reinfection. This could spread to parents, grandparents, and other clinically vulnerable individuals.
