Pfizer's COVID vaccine seems safe, effective 6 months later
Vaccine effectiveness (VE) for the Pfizer/BioNTech COVID-19 vaccine against COVID-19 was 91% up to 6 months after the second dose, according to a non–peer-reviewed study published yesterday on the preprint server medRxiv.
The researchers followed 44,060 people 16 and older, randomly assigning half to receive two doses of the Pfizer/BioNTech vaccine and half to a placebo. Most of the 152 recruitment sites were in the United States (130), followed by Turkey (9), Germany (6), and South Africa (4). The study also followed 2,260 US children 12 to 15 years old, with half receiving the intervention and half receiving placebo.
VE was 91.1% up to 6 months after the second vaccine dose, regardless of previous COVID-19 infection (95% confidence interval [CI], 89.0 to 93.2). Against severe disease it was 97% (95% CI, 80.3% to 99.9%).
When the researchers looked at VE across age, sex, race, or COVID-19 risk factors, VE was always 86% or higher, although they note that youth data was not available for 6 months because of when enrollment began (Oct 15, 2020, vs Jul 27, 2020, for adults). VE peaked at 96.2% from 7 days to less than 2 months after the second dose, but at 4 months it declined to 83.7%, with an average decline of 6% every 2 months.
More vaccine recipients reported local and systemic events than placebo recipients, with mild-to-moderate injection site pain and fatigue being the most common, respectively. People who had COVID-19 prior to vaccination reported more systemic reactions after the first dose, whereas those who were naive to COVID-19 reported more systemic reactions after the second. While 15 vaccine recipients and 14 placebo recipients died, none of the deaths were considered related to the intervention.
Because reactogenicity events among participants not in the reactogenicity subset were reported as adverse events, the researchers say that the data show imbalances toward the Pfizer group (30% vs 14% for adverse events, 24% vs 6% for related adverse events, and 1.2% vs 0.7% for severe adverse events).
"Despite a gradually declining trend in vaccine efficacy, BNT162b2 had a favorable safety profile and was highly efficacious in preventing COVID-19," the researchers conclude.
Jul 28 medRxiv study
Treated MIS-C shows favorable follow-up at 6 months, study says
In a longitudinal cohort of 25 children with multisystem inflammatory syndrome in children (MIS-C), all were asymptomatic and at their functional baseline at 6-month follow-up, according to a Pediatrics study yesterday. The study included a total of 50 children, with some lost to follow-up, but during all intermediary follow-ups, symptoms were improving.
All study participants were admitted to Cohen Children's Medical Center with MIS-C from Apr 17 to Jun 20, 2020 (median age, 8.5 years; range, 9 months to 17 years). Most patients exhibited rapid clinical improvement, with an average hospital stay of 5 days. At discharge, 69% of 26 patients with left ventricular (LV) systolic dysfunction had resumed normal function, 15% had persistent but improved dysfunction, and 15% had mild dysfunction at admission but no available discharge data.
At 2 weeks, 47 presented for follow-up, and 47% said they got tired with ordinary activities, most of them (81.8%) having experienced shock or myocardial systolic dysfunction at initial admission. All other patients were asymptomatic. Platelet levels were elevated compared with admission (median, 463,000 cells per microliter vs 172,000), but all other markers had normalized. Some LV systolic (one patient) and diastolic (five) function persisted.
The follow-up at 8 weeks involved 42 people, with 5 (12%) continuing to experience fatigue during regular activity. All LV systolic function was normal, and any remaining coronary aneurysms and dilation had resolved. However, 4 (9%) still had diastolic dysfunction, and 5 (12%) had qualitative coronary abnormalities.
By 6 months, the 25 available patients were asymptomatic and at their functional baselines. Despite being asymptomatic, one patient still had LV diastolic dysfunction, but cardiac magnetic resonance imaging at 8 weeks didn't show inflammation or fibrosis.
"Early and mid-term prognosis after hospitalization and immunomodulation treatment for MIS-C is excellent with return to functional baseline, normalized LV systolic function, and resolved coronary abnormalities. However, persistence of diastolic dysfunction in a few patients confounds our understanding of MIS-C," write the researchers.
Jul 28 Pediatrics study
Liberia battles Lassa fever outbreak marked by high case-fatality rate
Liberia is battling a Lassa fever outbreak with 13 cases confirmed so far, 9 of them fatal, reflecting a higher case-fatality rate than the country has recorded over the past 5 years, the World Health Organization (WHO) African regional office said in its latest weekly outbreaks and health emergencies report.
The confirmed cases were reported from January through early July among patients from four counties in central Liberia: Bong, Grand Bassa, Montserrado, and Nimba. Females make up 54% of cases, and all but three of the cases are in people older than 16. Sixty contacts are currently being followed, and the response has been stepped up in the affected counties.
Lassa fever is endemic in Liberia and other West African countries. The viral hemorrhagic illness is similar to Ebola, but it usually less likely to be fatal, though it can cause severe disease. The virus is spread by rodents and jumps to humans through contact with rodent urine and droppings. It can spread among humans through contact with body fluids.
Jul 25 WHO African regional office weekly report
Prepackaged salad recall expands in 3-state Salmonella outbreak
Bright Farms yesterday expanded its recall of packaged salad greens that have been linked to a Salmonella outbreak that has now sickened 11 people in 3 states, according to federal health officials.
The recall involves products packaged at its Rochelle, Ill., facility and were sold in Illinois, Iowa, Indiana, and Michigan, the Food and Drug Administration (FDA) said in a recall update. In addition to several products that were subject to a Jul 15 recall, the expansion yesterday includes baby spinach that was sold in 4- and 8-ounce packages. The product is past its expiration date. The expiration date for the previously recalled products is today.
Also, the Centers for Disease Control and Prevention (CDC) in an outbreak update yesterday said it has received reports of three more cases and one more affected state since its Jul 15 update: Michigan. The states with earlier cases include Illinois and Wisconsin. Of the 11 patients reported so far, 2 have been hospitalized, and no deaths have been reported.
The outbreak subtype is Salmonella Typhimurium. An investigation at the farm found samples that were positive for Salmonella Liverpool, and health officials are using the PulseNet national subtyping network to see if there are any people infected with that strain.
Jul 28 FDA recall update
Jul 28 CDC outbreak update