COVID-19 Scan for May 24, 2022

News brief

Study shows fourth dose of Pfizer COVID vaccine wanes faster than third

A study from Israel published today in BMJ shows that the effectiveness of a fourth dose of Pfizer-BioNTech's mRNA COVID vaccine waned faster than a third dose in adults ages 60 and older.

The study took place over 10 weeks beginning in January 2022, and compared outcomes of 69,623 adults with three doses of Pfizer with 27,876 adults who received four doses. The study was conducted when Omicron was the dominant strain in Israel.

During the 10 week follow-up period, 106 participants died, including 77 who had a third dose and 23 with a fourth dose.

To gauge breakthrough infections, the authors performed a matched analysis that compared positive cases to controls by week since vaccination. The added relative vaccine effectiveness of a fourth dose against infection quickly decreased over time, peaking during the third week at 65.1% (95% confidence interval [CI], 63.0% to 67.1%) and falling to 22.0% (95% CI, 4.9% to 36.1%) by the end of the 10 week follow-up period, the authors said.

"This study has shown additional protection of the fourth dose against both SARS-CoV-2 infection and severe covid-19 relative to three doses. However, the relative vaccine effectiveness against infection varied over time and waned sooner than that of the third dose," the authors said. "By the fifth week after vaccination, relative effectiveness of the fourth dose against SARS-CoV-2 infection dropped back to levels similar to those observed during the first week."
May 24 BMJ study

Study: COVID-19 vaccine protection lower, wanes faster in cancer patients

A UK study suggests that COVID-19 vaccination offers protection against infection, hospitalization, and death for most cancer patients but is less effective and wanes faster than in the general population.

In the study, published yesterday in The Lancet Oncology, a team led by University of Oxford researchers mined public data on English adults with and without cancer who had received two doses of a COVID-19 vaccine from Dec 8, 2020, to Oct 15, 2021, a period during which the Delta variant became dominant.

Among the 377,194 patients with active or recent cancer, 42,882 (11.4%) tested positive for COVID-19, compared with 5,748,708 of 28,010,955 (20.5%) controls without cancer. Estimated initial vaccine effectiveness (VE) was 65.5% (95% confidence interval [CI], 65.1% to 65.9%) among cancer patients and 69.8% (95% CI, 69.8% to 69.9%) among controls.

By 3 to 6 months, however, the difference in VE had widened, at 47.0% (95% CI, 46.3% to 47.6%) among cancer patients and 61.4% (95% CI, 61.4% to 61.5%) among controls. The COVID-19 vaccine offered more protection against hospitalization (83.3%) and death (93.4%) than against infection in cancer patients but also waned after 3 to 6 months.

Relative to controls, VE was much lower among patients with the blood cancers leukemia or lymphoma, a recent cancer diagnosis, or chemotherapy or radiotherapy within the past year.

"This highlights the importance of vaccination booster programmes and rapid access to COVID-19 treatments for people undergoing cancer treatments," senior author Peter Johnson, MD, of the University of Southampton, said in a University of Oxford news release.

In a related commentary, Nicole Kuderer, MD, of the Advanced Cancer Research Group, and Gary Lyman, MD, MPH, of the Fred Hutchinson Cancer Research Center, both of Seattle, said the results illustrate the importance of prioritizing cancer patients for additional vaccine doses, treatments, and preventive therapies.

"In the meantime, high-quality face masks and physical distancing offer important protection against any strain of SARS-CoV-2," they wrote.
May 23 Lancet Oncol study and commentary
May 23 University of Oxford news release

News Scan for May 24, 2022

News brief

Parts of Australia report early-season flu surge

Flu levels are up sharply in some Australian states, putting pressure on healthcare systems that are also coping with ongoing COVID-19 activity and prompting more efforts to get more people vaccinated against flu.

In New South Wales (NSW), hospital and lab surveillance shows sharp increases in flu activity earlier than seen in previous winter flu seasons, the state's health department said in its update for the week ending May 14. Influenza A is the dominant strain, with 2009 H1N1 more common in children and H3N2 affecting adults.

On Twitter, the NSW health department said emergency departments are under pressure due to COVID-19 and a rise in flu cases, and it urged people to consider other options for non-urgent medical care.

Meanwhile, Queensland state's health officials said yesterday that all residents will be offered free flu vaccination as the state faces a severe influenza A outbreak, with cases doubling every week. They said vaccine rates and immunity levels are low, and case numbers are climbing faster and earlier than expected. They said supply chain and health service disruptions from COVID-19 will be exacerbated by a simultaneous flu outbreak.
May 19 NSW COVID-19 and flu update
May 24 NSW health department tweet
May 23 Queensland government statement

In its latest global flu update, which roughly covers the last half of April, the World Health Organization (WHO) said flu activity decreased, with activity stabilizing or decreasing in temperate parts of the Northern Hemisphere. In temperate parts of the Southern Hemisphere, activity rose in Argentina and Chile.

The WHO added that flu detections increased in Australia in the last half of April, but levels were still below the 5-year average.

Globally, of respiratory samples that tested positive for flu during the reporting period, 98% were influenza A, and, of the subtyped influenza A samples, 93.5% were H3N2 and 6.5% were 2009 H1N1.
May 16 WHO global flu update

Canada reports avian flu in skunks as virus strikes more US flocks

Following detections of avian flu in foxes in Canada and the United States, veterinary officials in Alberta have detected the virus in skunks found dead, according to CTV News. The detections in wild mammals are notable, raising concerns about the zoonotic potential of the circulating virus.

Margo Pybus, PhD, a wildlife specialist for Alberta Fish and Wildlife, told CTV that the skunks that tested positive were in east-central Alberta. She said tests are also pending for some young foxes.
May 20 CTV story

In US developments, two states reported more highly pathogenic avian flu outbreaks in poultry flocks, according to the latest update from the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS).

Pennsylvania reported an outbreak at a commercial duck breeding farm in Berks County that houses 4,700 birds, and Wisconsin reported the virus in backyard birds in Bayfield County, which is on the southern shore of Lake Superior.

So far, the tests have confirmed the virus in 349 flocks across 35 states. The outbreaks have led to the loss of 38.02 million birds.

Yesterday, the World Organisation for Animal Health (OIE) urged farmers to boost their biosecurity practices against two big threats, avian flu and African swine fever. It said the avian flu activity since October 2021 is unprecedented, with 47 countries reporting nearly 3,000 outbreaks, resulting in the loss of 80 million domestic birds.

It also raised concerns about the impact of the virus on wild birds, which could affect biodiversity. For example, it said the virus has killed more than 8,000 cranes in Israel.
USDA APHIS poultry avian flu updates
May 23 OIE statement