American researchers say that people may not be infected with COVID-19 for 9 months or more after they test positive.
A new study found that the previous COVID-19 infection can provide at least two doses of high-quality mRNA vaccine (such as Modena vaccine and Pfizer vaccine)
In addition, the study also found that people infected with the virus can be free from reinfection for 40 weeks or more.
It was published in the Lancet on February 16.
For the ancestor (original) strains of COVID-19 and α、β and δ Variants have the highest protective effect on reinfection and remain above 78% after 40 weeks.
The protective effect of Omichron BA. 1 variant was relatively low, falling to 36.1% in the same time range.
A new study found that people infected with COVID-19 may be free from re infection within 40 weeks or more.
When it comes to serious diseases (hospitalization or death), the protective effect of all variants is very high. After 40 weeks of infection, ancestral α、β、δ The average protective effect of BA. 1 and Omixon is 78% or higher.
The protection level of all variants decreased with the passage of time, but the protection level of Omixon BA. 1 variant decreased the fastest.
The study, entitled "COVID-19 infection in the past to prevent reinfection: systematic review and meta-analysis", was led by a group of researchers from the COVID-19 prediction team.
The level of protection provided by COVID-19 infection in the past is at least the same as that provided by two high-quality mRNA vaccines.
Dr. Mark Siegel, a professor of medicine at the Langney Medical Center of New York University in New York City and a medical writer of Fox News, told the Fox News Digital Channel that immunity to previous infections (known as natural immunity) and immunity to vaccines can provide significant protection against serious diseases and some protection (at least a few months) to prevent re-infection of the virus.
"That's why I generally don't recommend using vaccine fortifiers at least a few months after infection," he said
Dr. Siegel said that the strongest immunity is the combination of the two (vaccination and virus infection), that is, the so-called mixed immunity, but he would never suggest anyone deliberately infected.
Dr. Marc Siegel said that he generally does not recommend the use of vaccine enhancers at least a few months after infection.
"It's too unpredictable in terms of disease outcomes and long-term COVID-19 risk," he said.
The results of this new study may challenge the vaccine demand policy.
The author of the study wrote: "This finding is also important for formulating policies that restrict travel or activity places or require workers to be vaccinated."
"It supports the view that those with documented infections should receive treatment similar to those who have been fully vaccinated with high-quality vaccines."
Researchers analyzed 65 studies from 19 countries.
These studies compared people who had recovered from COVID-19 and those who had not been infected before September 31, 2022.
When evaluating infection cases, researchers considered the severity of symptoms, the variation of virus and the time when people tested positive.
The author points out in the research results that this is the first time to "comprehensively evaluate the natural immune protection against COVID-19 reinfection through mutation (primary infection and reinfection), and evaluate the decline of immunity over time since the primary infection."
As of February 15, the US Centers for Disease Control and Prevention reported an average of 259339 new cases of COVID-19 every week.
This study does have some limitations.
For example, the number of studies to be evaluated is very small, and the data over 40 weeks is not much.
In addition, the study relied on different methods to determine the past infection status, including antibody detection and viewing the previous COVID-19 test results.
As of February 15, only 16% of Americans had received the enhanced dose of the updated COVID-19 vaccine, while 69% had completed a series of primary vaccines
As of February 15, the US Centers for Disease Control and Prevention (CDC) reported that 259339 new COVID-19 cases were added every week on average.
The peak was 5.6 million cases per week in January 2022.
Only 16% of the US population received the updated COVID-19 vaccine booster dose.
At the same time, 69% of the population completed a series of primary vaccines.