Ômicron may cause more reinfection than delta variant, studies show

Booster doses of Covid-19 vaccines significantly restore protection against mild symptoms caused by the omicron variant of the virus, the British Health Security Agency said on Friday, in part reversing a decline that would have been acute in the virus. effectiveness of immunizing agents.

Preliminary findings from an empirical analysis are some of the first data on protection against omicrons that do not come from laboratory studies, according to which the neutralizing activity of vaccines is reduced in the case of the new variant.

“These preliminary findings should be taken with caution, but they indicate that a few months after the second dose of vaccine there is a greater risk of contracting the omicron variant than the delta variant,” said Mary Ramsay, director of Immunization at the UK agency.

She highlighted that the expectation is that the protection against severe symptoms provided by the booster dose will remain higher.

“The data suggest that the risk of serious illness is significantly reduced after the booster vaccine. Therefore, I recommend that everyone take the booster dose when it is available to them.”

An analysis of 581 people tested with omicron revealed that two doses of AstraZeneca or Pfizer-BioNTech vaccine provided levels of protection against symptomatic infection far below the protection they would guarantee against the delta variant.

But with a booster dose of the Pfizer vaccine, the level of protection against symptomatic infection rose to 70% among people who had initially taken the AstraZeneca vaccine and to 75% among those immunized with Pfizer.

For people infected with the delta variant, the level of protection after the booster dose is estimated to be 90%.

The British agency reiterated its finding that omicron is more transmissible than delta and that the risk of reinfection with the variant is between 3 and 8 times higher.

The agency said that two British studies that have not yet been publicly presented and three international studies suggest that omicron causes a very strong reduction in neutralizing antibodies, compared to the viruses used to develop vaccines.

The agency also said that while no omicron cases have yet resulted in hospitalization or death, the available data are insufficient to assess the severity of the strain.

reinfection

Other evidence that omicrons causes more reinfection has been obtained in the United States. Of 43 confirmed cases of the new variant in the US, 34 people were fully vaccinated, according to the Centers for Disease Control and Prevention (CDC).

In addition, 14 of them had taken the booster dose, but 5 of these cases occurred less than 14 days after application, before the additional protection took effect.

The omicron was found in 22 US states as of Friday (10). Of the identified cases, 25 are from people aged between 18 and 39 years of age and 14 have traveled internationally. Furthermore, 6 had been previously infected with the coronavirus.

Most had only mild symptoms such as coughing, congestion and fatigue, according to the report released, and one person was hospitalized for two days. Other less frequently reported symptoms included nausea or vomiting, shortness of breath or difficulty breathing, diarrhea, and loss of taste or smell.

The CDC said there is a time lag between the infection and the onset of more severe symptoms, so they can’t rule them out for now. Symptoms are also expected to be milder among people vaccinated or previously infected with SARS-CoV-2.

Even if most cases are mild, a highly transmissible variant could result in enough cases of Covid to overwhelm health systems, the CDC said.