Two-dose COVID vaccine efficacy durable against severe Omicron but drops in elderly

News brief

Overall two-dose vaccine effectiveness (VE) against Omicron variant-related hospitalization or death remained above 70% for at least 6 months among adults in Hong Kong but dropped to below 62% in those aged 80 and older, necessitating a third dose, finds a case-control study published today in JAMA Network Open.

Hong Kong researchers used linked administrative data to estimate VE of the CoronaVac and Pfizer/BioNTech COVID-19 vaccines among 32,823 adults who died or were hospitalized due to Omicron from Jan 1 to Jun 5, 2022 (case participants) and 131,328 infected control participants listed in a public health registry during the same period. The average age in both groups was 65 years.

Greater than 90% VE after booster

Most (62.1%) of the 9,362 case participants who died and 49.5% of the 16,236 who died or were hospitalized were unvaccinated, compared with 37% of 37,488 and 21.4% of 131,328 controls, respectively.

VE against severe disease rose with the number of doses for both types of vaccine. The overall VE of CoronaVac against death climbed from 56.4% after one dose to 71.1% after two doses to 88.5% after three. VE of the Pfizer vaccine against death increased from 62.2% after one dose to 70.8% after two doses to 84.4% after the third.

For at least 6 months, VE against severe outcomes after a second dose of the CoronaVac and Pfizer vaccines was 74.0% and 77.4%, respectively. Two-dose VE against death in participants aged 18 to 49 years was 86.4% and 92.9% among CoronaVac and Pfizer vaccine recipients, respectively, but fell to a respective 61.4% and 52.7% in those aged 80 and older after 6 months.

A booster dose is recommended for older patients to restore immunity.

Four to 6 months after the third dose, overall VE against death was greater than 90% for CoronaVac and Pfizer vaccines and among participants who received a combination of the two.

"A booster dose is recommended for older patients to restore immunity," the authors wrote. "This is especially critical in a setting like Hong Kong, where third-dose coverage is still insufficient among older residents."

TB Alliance to partner with Qurient on new TB drug

News brief

TB Alliance and South Korean biotechnology company Qurient Co. Ltd. announced today that they have entered into a license agreement to develop and commercialize a novel tuberculosis (TB) drug.

Under the terms of the agreement, TB Alliance will obtain the exclusive worldwide license for telacebec (Q203), a first-in-class investigational drug that inhibits the ability of Mycobacterium tuberculosis to generate energy. Telacebec has demonstrated potent efficacy against drug-sensitive and drug-resistant TB in preclinical and clinical studies and has received Orphan Drug and Fast Track designation from the US Food and Drug Administration (FDA).

"We believe telacebec will greatly contribute to the global efforts to combating the TB pandemic, which remains a serious public health challenge worldwide," Qurient CEO Kiyean Nam, PhD, said in a press release. "Our partnership with the TB Alliance will accelerate the widespread availability of telacebec and bring it to those in need."

TB Alliance CEO Mel Spigelman, MD, says new drugs with novel mechanisms are urgently needed in the fight against TB. A recent report from the World Health Organization (WHO) found that global TB cases rose 4.5% in 2021 amid a reduction in essential TB services linked to the COVID-19 pandemic.

"If we expect to regain ground lost to COVID-19, we need to use every tool we have to give patients the best possible treatment and save lives," Spigelman said. "We look forward to advancing this new compound as part of combination regimens that could yield a short, simple, safe, and highly effective cure for all forms of TB."

Cefiderocol now available in Denmark, Norway

In other antibacterial news, Japanese drugmaker Shionogi announced this week that the novel antibiotic cefiderocol is now available in Denmark for the treatment of infections caused by gram-negative bacteria in patients who have limited treatment options.

Approved by the FDA in 2019 and by the European Medicines Agency in 2020, cefiderocol has demonstrated in vitro activity against multidrug-resistant gram-negative bacteria, including those identified by the WHO as critical priority pathogens. The drug, which has been used in more than 23,000 patients in Europe, became available in Norway in January.

Quick takes: Nigeria Lassa emergency, measles in Paraguay, new polio cases

News brief
  • The Nigeria Center for Disease Control and Prevention on Jan 30 activated its emergency operations center to boost its response to an unprecedented spike in Lassa fever cases compared to previous years. The rise has come with an increasing number of states reporting cases and rising numbers of healthcare worker infections.
  • Paraguay has reported its first local measles case since 1998, which involves a 14-month-old boy who was sick in September and had recently received one vaccine dose, the World Health Organization said yesterday in an outbreak notice. Genetic analysis by the US Centers for Disease Control and Prevention revealed that the virus didn't match the vaccine strain. Though the boy had no travel history, one of his contacts had similar symptoms and has a family member who frequently travels to Buenos Aires, Argentina.
  • Five countries reported more polio cases this week, all involving circulating vaccine-derived poliovirus type 2, the Global Polio Eradication Initiative said in its weekly update. Affected nations are the Central African Republic (1 case), Chad (7), Indonesia (1), Nigeria (1), and Yemen (1). All new infections are included in country totals for 2022 except the case in Indonesia, which is its first of 2023 and marks its second such case.

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