Brazilian study suggests increased risk of reinfection by Delta variant

RIO DE JANEIRO, BRAZIL – According to researchers, the serum of people previously infected by other strains of the disease is less potent against this viral variant.

The Delta variant of the novel coronavirus increases the risk of reinfection by Covid-19, according to a recently published study conducted by the Oswaldo Cruz Foundation (Fiocruz).

On Monday, the foundation provided further details on its research on the Delta variant, initially detected in India. In the study, researchers suggest that serum from people previously infected by other strains of the disease is less potent against this viral variant.

According to Fiocruz, the research was published in Cell scientific journal, and was led by UK’s Oxford University. To conduct the study, 59 researchers from the UK, China, Brazil, United States, South Africa, and Thailand participated in a scientific collaboration.

In the case of Brazilian researchers, the Respiratory Virus and Measles Laboratory of the Oswaldo Cruz Institute (IOC/Fiocruz), the Laboratory of Ecology of Communicable Diseases in the Amazon of the Leonidas and Maria Deane Institute (Fiocruz Amazônia), and the Health Surveillance Foundation of Amazonas (FVS/AM) were involved.

According to the study’s findings, reinfection by the Delta variant is markedly observed among individuals previously infected by the Gamma variant, originally identified in Manaus and currently dominant in Brazil, as well as by the Beta variant, first detected in South Africa.

Among people previously infected with both the Gamma and Beta strains, the ability to neutralize the Delta strain is 11 times lower, Fiocruz pointed out, using information from the study as a basis.

In addition, the serum from vaccinated people also has reduced potency against the Indian variant – although the data point out that the vaccines remain effective, but to a lesser extent, Fiocruz noted.

According to the study, the ability to neutralize the Indian strain is 2.5 times lower for Pfizer’s vaccine and 4.3 times lower for Astrazeneca’s, said the researchers in the Delta variant study.

According to the researchers, the analyses of the new study show that the affinity of the Delta variant to cell receptors is higher than that observed in the strains circulating at the start of the pandemic. However, it is lower than with the other variants observed after the disease emerged in March 2020.

In order to reach their conclusions, the researchers analyzed the action of 113 sera, obtained from infected and immunized patients, on 6 strains of the novel coronavirus.

Fiocruz recalls that the Delta variant is a subtype of the B.1.617 viral strain, which emerged in India in October 2020. In May this year, after being associated with the worsening of the pandemic in India and the UK, the strain was declared a variant of concern by the World Health Organization (WHO).

According to the WHO, the variant is circulating in at least 85 countries worldwide. In Brazil, infections caused by the Delta variant have been diagnosed in travelers in Maranhão, Rio de Janeiro, Minas Gerais, Paraná, and Goiás, according to the Ministry of Health.

On June 19, the Municipal Health Secretariat of Goiânia confirmed the first record of the strain’s local transmission.

Source: Valor