A study by Public Health England (PHE) claimed that people previously infected with the Coronavirus have greater protection against repeated infection after 5 months, than those who receive the Oxford vaccine.
The researchers also claimed that these individuals have the same level of immunity as the Pfizer vaccine.
Data from the PHE SIREN study, which tracks more than 20,000 healthcare workers in more than 100 locations across Britain, looked at how many members of the NHS team in the study group had contracted the virus more than once.
A total of 6,614 workers were found infected with the virus in early 2020, either through antibody testing, PCR swabs, or clinical evaluation based on symptoms.
Only 44 people from this group were confirmed to be infected with the Coronavirus, as a result of repeated infection.
PHE researchers say this means that a previous infection provides 83% protection against re-infection, as well as reduces the likelihood of symptoms and severe disease.
The researchers gave the participants monthly antibody tests as well as weekly PCR swabs, to monitor for any infections between June and November.
This methodology allowed the researchers to capture people with symptoms, as well as those without symptoms.
Professor Susan Hopkins of PHE, the lead author of the study, says this method is more rigorous than used for testing vaccines, which relies only on symptomatic states.
In the PHE study, only 15 of the 44 infected individuals showed symptoms.
Professor Eleanor Reilly, from the University of Edinburgh, who was not involved in the research, said: “The message from this study is that the initial infection with SARS-CoV-2 provides at least 94% protection against the recurrence of symptoms in at least five months. Indicates that natural infection provides short-term protection against “Covid-19″, very similar to that given by vaccination. ”
Hopkins said at a press conference, that the protective effect of the previous infection is almost as strong as the effect of the “Pfizer” vaccine, and “much better” than the Oxford / AstraZeneca vaccine, which recorded an efficacy rate of 62.1% in participants who received twice standard doses.
PHE researchers have classified re-infections as possible, but are unable to say with certainty due to the fact that PCR tests and genome sampling were not widely available during the first wave.
Nevertheless, 44 cases (2 probable and 42 probable) fulfilled the criteria that led to their inclusion in the study, including a positive test for SARS-CoV-2 infection.
“The results will help in giving, along with the vaccine, the ability to slow the transmission of the virus. But it is not complete protection and people still need to be careful when going out, moving around and take precautions,” Hopkins said.
And the researchers could only say that the length of time that natural immunity lasts is five months, because that was the duration of the study.
Hopkins added: “This study gave us the clearest picture so far of the nature of antibody protection from” Covid-19 “, but it is important that people do not misunderstand these early results. We now know that most of those who have been infected with the virus, and have developed antibodies, are protected from infection once. Other, but this is not entirely, and we do not yet know the term of protection. ”
SIREN’s trial will last for 12 months, and more data will be released soon, which will reveal how the variables of the new Corona virus have affected rates of infection again, and whether normal immunity has a time limit.
However, researchers found in people who were infected with the Coronavirus but without symptoms, evidence that they had high viral loads, indicating that they would be able to transmit the infection to other people despite not feeling sick.
But Riley says re-infection is so rare that people who have been previously infected are “less likely to transmit the virus to others.” This is good news in terms of the long-term trends of the pandemic.
However, asymptomatic cases of infection are not zero, so you cannot assume that just because you had the virus before, you cannot be contagious.
These data reinforce the message that, at present, everyone should view themselves as a potential source of infection for others, and act accordingly.
Source: Daily Mail