The protection afforded by surviving COVID-19 was strong against the latest virus subvariants, including the one currently dominant in the United States, scientists in Qatar found.
People who were infected with Omicron, a variant of SARS-CoV-2, had 76.1 percent protection against symptomatic reinfection from BA.4 and BA.5 and 80 percent shielding from any reinfection, regardless of symptoms, according to the preprint study.
SARS-CoV-2, also known as the CCP (Chinese Communist Party) virus, causes COVID-19.
Omicron became the dominant virus strain in many countries in late 2021. Since then, a number of subvariants have taken hold. BA.5 is the strain currently dominant in the United States.
While protection from an Omicron infection provided robust shielding against reinfection, those who contracted a pre-Omicron strain had little protection, according to the Qatari scientists, who were led by Dr. Laith Abu-Raddad with Weill Cornell Medicine-Qatar.
Pre-Omicron infection provided just 15.1 percent effectiveness against symptomatic BA.4 and BA.5 reinfection and just 28 percent infection against any reinfection.
The scientists analyzed data from national COVID-19 databases.
Infections before Omicron were those that occurred before Dec. 19, 2021, when the variant wave started in Qatar.
“Protection of a previous infection against BA.4/BA.5 reinfection was modest when the previous infection involved a pre-Omicron variant, but strong when the previous infection involved the Omicron BA.1 or BA.2 subvariant,” the scientists wrote.
Natural immunity has long been found to be superior to the protection from COVID-19 vaccines, and the new study is no exception. Vaccines provide little protection against Omicron infection and perform worse against infection and severe illness from the BA.4 and BA. 5 subvariants, studies have shown.
Natural immunity also waned against BA.4 and BA.5, highlighting how the subvariants are better at evading protection, the Qatari researchers found.
The group has been studying natural immunity for years and recently discovered that the protection from prior infection against severe disease showed no signs of waning, regardless of what strain infected the person.
Among the listed limitations for the new study was the young population of Qatar, where just 9 percent of residents are 50 years of age or older. That means the findings “may not be generalizable to other countries where elderly citizens constitute a larger proportion of the total population,” researchers wrote.
Some experts, including Abu-Raddad and U.S. Centers for Disease Control and Prevention Director Dr. Rochelle Walensky, continue recommending vaccination for people with natural immunity, pointing to studies that indicate one or more doses increase protection, but others say vaccination isn’t needed for people who survive COVID-19, since some research suggests the elevated protection is minimal and that the naturally immune are at higher risk of vaccine side effects.
Canada greenlights Moderna jab for infants
Nearly 2 million children between the ages of six months and five years are now eligible to receive a coronavirus vaccine
Canada’s drug regulator has approved Moderna’s coronavirus vaccine for babies, toddlers, and preschoolers, the first jab to receive authorization for the age group.
The Public Health Agency of Canada announced the decision on Thursday, saying it approved a two-dose vaccine series for children aged six months to five years “after a thorough and independent scientific review of the evidence.”
The National Advisory Committee on Immunization recommended smaller doses for children, just one-quarter of the amount approved for adults, citing phase three trial results for the Moderna shot.
The vaccines should be administered about eight weeks apart, especially for those who currently have the virus, though immunocompromised patients could receive doses at an interval of just four weeks, it added.
While the health agency acknowledged “most children” who contract Covid-19 have “no or mild symptoms,” it noted that “some, including previously healthy children, can get very ill and require hospitalization,” suggesting vaccination could avoid such outcomes.
Health Canada cautioned that due to a lack of long-term data for the vaccine, there is currently little information about serious side effects such as myocarditis – a potentially lethal heart condition seen in some older recipients – for the age group. It said it had not seen any severe adverse reactions during Moderna’s trials, however.
The US approved the use of Pfizer and Moderna’s coronavirus shots for the same six-month to five-year-old age group last month, and has since inoculated around 267,000 children as of July 8, according to the US Centers for Disease Control and Prevention.