In one of the most intriguing and worrying developments in the pandemic, scientists are rushing to explain what is happening in Manaus, Brazil, a city of 2.2 million people on the edge of the country’s rainforest that is experiencing a second explosive outbreak. , even though the former was so bad that it was thought to have produced collective immunity.
As the situation deepens in Manaus, overloading the city’s health system again, researchers from Brazil and the UK said yesterday that four possibilities could explain the recent dramatic resurgence, including the variant of the SARS-CoV-2 virus that emerged in Brazil . They published their analysis yesterday in The Lancet.
The outbreak in the city last spring surprised the world with images of corpses in the streets, people buried in cardboard coffins and mass graves in local cemeteries. Seroprevalence studies during the summer estimated that 76% of Manaus residents were infected, above the basic herd immunity limit of 67%.
However, a new outbreak that began in December invaded the health system again, prompting calls for other countries to help by sending oxygen supplies.
Doctors on the front line say the second outbreak overwhelmed hospitals much faster than the first and that patients are reaching the sickest hospitals, leading some to suspect that a new variant is circulating, that it is not just more communicable, but it can also be more lethal, according to Washington Post. Noaldo Lucena, MD, infectious disease specialist at Tropical Doctor Heitor Vieira Dourado, in Manaus, told the Post. “This is not a feeling. It is a fact.”
A false sense of security, with some government officials minimizing the threat, going to the Christmas holiday may also have caught Manaus off guard, as illnesses began to increase again in December, according to the Post.
At the Lancet report, experts said four factors may be at play, some possibly related. First, scientists may have overestimated the attack rate for the first outbreak and infections may have been below the herd’s immunity limit. Second, immunity in people infected in the first wave may have declined in December, which they said would not fully explain the resurgence.
Another factor could be the circulation of SARS-CoV-2 variants, some of which originated in Brazil, which prevent the immune response from previous infection with the original virus. And as a fourth possibility, variants circulating in the second wave may be more transmissible than the virus that fed the first wave.
The authors referred to the discovery of the P.1 variant in Manaus, which began to appear in December with frequent detections. Although little is known about the variant, it shares mutations with variants from the United Kingdom and South Africa that can make it more transmissible.
PAHO suggests P.1 fueling increase in Manaus
The latest epidemiological update from the Pan American Health Organization (PAHO) provides more details on the local transmission of P.1 in Manaus, which appears to be based on an analysis of sequencing data by a team from the Arbovirus Discovery Center, Diagnostics, Genomics and Epidemiology (CADDE) Genomic Network and published on January 12 on Virological.org.
The researchers wrote that the P.1 variant was only detected in Manaus after November and that in December it represented 52.2% of the genotyped samples. In January, the proportion soared to 85.4%. They also saw an increase in the P.2 variant in December, which was at 25.4%, but has since dropped to 6% in January.
Emphasizing that the findings are preliminary, the group said that P.1 appears to be conducting local transmission in Manaus, although P.2 and other strains may still be circulating.
PAHO said today in a statement about the variants circulating in the Americas that mutations are expected, which underscores its advice to countries to continue to strengthen their COVID-19 measures and virus surveillance.
Regarding the variant that circulates in Manaus and throughout the Amazon region, Sylvain Aldighieri, MD, the group’s incident manager, the researchers suggested a causal link for the increase in hospitalizations in Manaus, “But it is too early to conclude about the strength of the association between the emergence of the variant and the recent dynamics of transmission. “
Vietnam reports new outbreaks
In its first local cases in almost 2 months and in its highest total in a single day, Vietnam yesterday reported 84 new cases in two northern provinces, Hai Duong and Quang Ninh, according to Reuters. State media said cases were also detected in Bac Ninh province and Hai Phong, a port city.
Vietnam is among the countries that received praise for keeping their cases and deaths of COVID-19 at very low levels.
The events led to a flurry of urgent response actions, including mass testing in the affected areas, suspension of international flights and a ban on meetings before the Lunar New Year.
The government said that some of the cases may be linked to the B117 variant that was first detected in the UK, according to the New York Times.
European Ebbing cases, WHO mission in China
In other international headlines:
- Thirty European countries, some in confinement, have reported declines in COVID-19 cases in the past 2 weeks, but several schools, hospitals and nursing homes have reported outbreaks involving the variant virus, Hans Henri Kluge, MD, MPH, who runs the office European regional body of the World Health Organization (WHO) said today. He said the region faces a “pandemic paradox”, with vaccines offering new hope, but variants posing a serious threat.
- Portugal today extended its national blockade and announced international travel bans, with crowded hospitals, according to Reuters. The country currently has the highest 7-day average per capita in the world for cases and deaths, and Germany has sent doctors to help.
- The joint WHO mission in China to investigate the animal origin of SARS-CoV-2 has ended its 2-week quarantine in Wuhan and will begin its face-to-face activities, according to Reuters.
- The global today has surpassed 101 million and is now in 101,253,267 cases, with 2,184,718 deaths, according to the online panel Johns Hopkins.