News Scan for May 02, 2022

Workplace COVID vaccination incentive
Flu vaccines and cardiac events
Japanese encephalitis in Australia

COVID vaccine uptake at Minnesota workplace rose after $1,000 incentive

The rate of full COVID-19 vaccination among employees of a private Minnesota medical device manufacturer rose 10.4 percentage points after the company began offering $1,000 incentives for immunization, finds a study published late last week in JAMA Network Open.

Researchers from Starkey Hearing Technologies and the University of Minnesota studied COVID-19 vaccination outcomes at Starkey from the incentive period of Aug 6 to Sep 30, 2021. Employees who agreed to watch and acknowledge an online educational program and show proof of two doses of an mRNA vaccine received $1,000 in October.

Data, including the vaccine brand and dates of each dose, were entered into a human resources database and combined with information on employee age, salary band, sex, and race.

By Sep 30, 2,055 of 2,099 (97.9%) workers eligible for the incentive reported their vaccination status. Of the 2,055 employees, 54.7% were women, 75.5% were White, 12.5% were Asian, and 6.8% were Hispanic.

Before the incentive was offered, 75.7% of employees were fully vaccinated against COVID-19, a figure that rose to 86.1% after, for a 10.4 percentage-point increase. Of 500 employees who had received one or no vaccine doses before, 42.8% were fully vaccinated by study end.

In the weeks leading up to the incentive announcement, rates of employees receiving their first and second vaccine doses were flat. But the week of the announcement, 54 more employees (95% confidence interval [CI], 29 to 79) received their first vaccine dose, and 70 more workers (95% CI, 30 to 110) received their second dose.

A higher proportion of women than men were vaccinated after the incentive was offered (45.3% vs 38.2%). Compared with their White and Black counterparts, Asian workers had higher levels of vaccine uptake (52.4% vs 43.6% vs 15.4%). Vaccination rates didn't differ significantly by age-group or salary range.

"Limitations of the study include absence of a control group, being limited to a single company, and possible confounding with full approval of the Pfizer vaccine by the FDA on August 23, 2021," the study authors wrote.
Apr 29 JAMA Netw Open research letter


Flu vaccination associated with 34% lower risk of cardiac events

A new meta-analysis of six randomized controlled trials finds that seasonal influenza vaccination was associated with a 34% lower risk of major adverse cardiovascular events, and people with a recent acute coronary event had a 45% lower risk. The study also appeared in JAMA Network Open.

The studies took place from 2000 to 2021 and included participants who were randomized to receive either a flu vaccine or placebo. The studies included 9,001 patients at an average age of 65.5 years; 52.3% had a previous cardiac event.

The authors found that 3.6% of vaccinated patients developed a major adverse cardiovascular event within 12 months of flu vaccination, compared with 5.4% of those who received placebo or control. This means 56 people would have to be vaccinated to prevent 1 cardiac event.

All told, 1.7% of vaccine recipients died of cardiovascular causes, compared with 2.5% of placebo or control recipients, for a 26% lower risk (risk reduction, 0.74; 95% confidence interval, 0.42 to 1.30; P = .29).

"The effect sizes reported here for major adverse cardiovascular events and cardiovascular mortality (in patients with and without recent ACS [acute coronary syndrome]) are comparable with—if not greater than—those seen with guideline-recommended mainstays of cardiovascular therapy, such as aspirin, angiotensin-converting enzyme inhibitors, β-blockers, statins, and dual antiplatelet therapy," the authors concluded.
Apr 29 JAMA Netw Open


WHO details Australia's recent Japanese encephalitis virus spike

Since March, when Australia declared a communicable disease incident of significance after a locally acquired case of Japanese encephalitis virus (JEV), the country has reported 35 cases—25 suspected and 12 probable—across four states, the World Health Organization (WHO) said in an outbreak notice last week.

Three deaths were reported, and the latest symptom onset was Mar 14.

The cases are the first on Australia's mainland since 1998. JEV is a mosquito-borne virus that mainly affects pigs and horses, but infectious pigs can amplify circulation in mosquitoes, which can transmit the disease to humans. The four affected states are New South Wales, Queensland, South Australia, and Victoria.

The cases this year are unusually high, given that Australia had reported only 15 JEV cases over the past decade. Of those, only 1 was acquired in Australia.

As of Apr 20, JEV has been detected on 73 pig farms across the same four states. Scientists are working to determine which mosquito species are most important in the spread of the disease in Australia. The WHO added that most cases are asymptomatic, but in those with clinical disease, the case-fatality rate can be as high as 30%, and some neurologic consequences can be permanent. There are no treatments, and vaccination is usually only advised for people in certain risk groups.

The onset of colder months in southern Australia could reduce mosquito populations and transmission, the WHO said, adding that the regional and global risk level is currently low.
Apr 28 WHO outbreak notice
Mar 4 CIDRAP News scan

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