Study: Omicron caused 3 times as many deaths as Delta in Massachusetts
More adults died of COVID-19 in Massachusetts in the first 8 weeks of the SARS-CoV-2 Omicron variant surge than in the entire 23-week Delta period, suggests a modeling study published today in JAMA.
A team led by a Brigham and Women’s Hospital researchers estimated excess deaths—a higher-than-expected number of fatalities—during Delta dominance (Jun 28 to Dec 5, 2021), the transition to Omicron (Dec 6 to 26, 2021), and Omicron dominance (Dec 27, 2021, to Feb 20, 2022) in Massachusetts.
The team applied models to 2014 to 2019 US Census population data and Massachusetts Department of Health all-cause death data from Jan 5, 2015, to Feb 8, 2020. They determined the variant periods using regional wastewater sampling data.
More excess deaths occurred in the 8-week Omicron period (2,294; 12,231 observed, 9,937 expected) than in the 23-week Delta surge (1,975; 27,265 observed, 25,290 expected), suggesting that Omicron—despite it generally causing milder infections—was deadlier overall. The per-week incidence rate ratio of Omicron to Delta for excess death was 3.34.
All adult age-groups saw statistically significant excess deaths during both periods, although more deaths occurred in older adults.
“In terms of excess death, we found that Omicron was actually much worse for Massachusetts than Delta,” lead author Jeremy Faust, MD, said in a Brigham and Women’s news release.
If Omicron causes less severe COVID-19, he said, “What we’re seeing here may reflect just how much more infectious Omicron has been. This could mean that highly contagious variants, even if they cause relatively milder illness, can still lead to substantial excess mortality, even in a highly vaccinated population.”
May 20 JAMA research letter
May 20 Brigham and Women’s Hospital news release
People with low body weight show less waning COVID vaccine immunity
A new study shows significantly less antibody waning 6 months after two doses of the Pfizer-BioNTech COVID-19 vaccine in people with low body weight, suggesting that those adults could wait longer than 6 months for a booster dose. The study appears in JAMA Network Open.
The small study involved 50 South Korean young adult healthcare workers who received the standard series of Pfizer vaccine and had not had a previous infection with COVID-19. Eighty percent of participants were women. Serum samples were collected at 2, 4, and 6 months after vaccination series was complete.
In all participants, anti–SARS-CoV-2 antibodies were maintained at high levels at 2 months (median, 93%) and 4 months (median, 91.5%) but decreased at 6 months (median, 84.5%). The decrease was inversely correlated with body mass index (BMI).
In adults who weighed 55 kilograms or less (roughly 122 pounds), anti–SARS-CoV-2-specific antibodies were higher at 2, 4, and 6 months after the second vaccine. In multiple linear regression analysis for women in the study, a 1–standard deviation increase in body weight, weight-to-height ratio, and BMI was associated with a 4% to 5% decrease in anti–SARS-CoV-2 antibodies.
“The negative association of body weight with antibody response after SARS-CoV-2 BNT162b2 mRNA vaccination suggests that individuals with overweight may have less immunity with a fixed-dose vaccine, but it is difficult to generalize because of the small sample size,” the authors wrote.
May 19 JAMA Netw Open study
Three US states report more avian flu, Gabon confirms first H5N1 outbreak
Three states reported more highly pathogenic avian flu in poultry, none involving commercial birds, according to the latest update from the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS).
They include a location in Colorado’s Jefferson County that has 10 birds but isn’t involved in animal production.
Idaho reported 4 more outbreaks involving backyard birds, 2 in Ada County and 2 in Canyon County.
In the Midwest, Indiana reported an outbreak in backyard birds in Allen County.
The outbreaks are part of ongoing activity involving the Eurasian H5N1 strain, which has struck poultry in 35 states and led to the loss of 37.9 million birds.
USDA APHIS highly pathogenic avian flu in poultry updates
In global developments, Gabon reported its first H5N1 outbreak, which occurred at a commercial farm in Estuaire province, which surrounds the country’s capital and largest city Libreville, according to a notification from the World Organisation for Animal Health (OIE).
The virus killed 15,000 of 15,500 susceptible birds. Officials said a further investigation is underway amid reports poultry deaths at other locations, including a live-animal market.
May 19 OIE report on H5N1 in Gabon
African nations report more vaccine-derived polio cases
Five African nations reported more polio cases this week, mostly involving circulating vaccine-derived poliovirus type 2 (cVDPV2), the Global Polio Eradication Initiative (GPEI) said in its latest weekly update.
Earlier this week, Mozambique reported a wild poliovirus type 1 (WPV1) case, its first such case in three decades. It also reported three new cVDPV2 cases, bringing its total for the year to four. The new cases were in Nampula province in the northeast and Manica province in the west central part of the country. The recent WPV1 case was detected in Tete province in the northwest.
Elsewhere, Chad, Niger, and Togo all reported their first cVDPV2 cases of 2022, Chad’s from Hadjer Lamis province, Niger’s from Maradi province, and Togo’s from Savanes province. Also, Nigeria reported 3 more cases in Kwara and Sokoto states, lifting its total for the year to 24.
May 19 GPEI update
May 18 CIDRAP News scan on WPV1 in Mozambique