In an update on the JN.1 variant late last week, the US Centers for Disease Control and Prevention (CDC) said the variant—steadily expanding its dominance—may be intensifying the spread of COVID-19 this winter. In the January 5 update, the CDC said COVID activity is high, but infections are causing less severe disease than earlier in the pandemic.

The variant, part of the BA.2.86 lineage, accounts for about 62% of variants, up from 44% 2 weeks ago. Also, the CDC said it is seeing an increase in JN.1 prevalence in international travelers and in wastewater in all US regions. JN.1 is dominant in Europe and is rising sharply in Asia.

Low vaccine uptake

Though test positivity and wastewater levels are moderately higher than last year at this time, emergency department visits are trending a bit lower over the same period.

The uncoupling of infection levels and illness severity is related to greater immune protection from previous disease, vaccination, or both, the CDC said, adding that more than 97% of people have antibodies against SARS-CoV-2. "This immune protection can fade over time but tends to last longer for preventing severe disease than for preventing infections," the agency said.

Long COVID remains an important health threat, and the CDC warned that not enough Americans have received the updated vaccine, with uptake at bout 8% in children and 19% in adults. For seniors, 38% have gotten the latest vaccine, "which is concerning given that they are at higher risk of hospitalization from COVID-19."

An observational study from Malaysia during a SARS-CoV-2 Omicron variant surge suggests that 3.4% of adult COVID-19 survivors had persistent symptoms 3 months after infection, with 1 in 5 saying the symptoms limited their ability to perform activities of daily living and 1 in 3 saying they were less able to work.

The results of the investigation, conducted from April to June 2022, were published late last week in PLOS One.

Most of the 44,386 participants were women, aged 30 to 59 years, recipients of a high school education, and had been fully vaccinated against COVID-19. A quarter of participants (25.7%) had chronic conditions, the most common of which were obesity, high blood pressure, and diabetes. About the same number (24.6%) had symptoms during infection, 2.5% were hospitalized, 0.6% needed supplemental oxygen, and 0.3% received intensive care.

Cough, fatigue, memory loss most common

A total of 44,386 participants completed online questionnaires at baseline and 3 months after diagnosis, 1,510 (3.4%) of them meeting the criteria for long COVID. The most common symptoms were cough (50.6%), fatigue (45.8%), memory loss (37.4%), shortness of breath on exertion (31.3%), impaired ability to focus (27.8%), headache (26.5%), muscle or joint pain (25.8%), and insomnia (23.4%). 

As the symptoms cut across multiple organ systems, management of individuals affected by this condition will likely require, or benefit from, dynamic and coordinated cross-sectoral interventions involving multiple specialties.

Women, those aged 30 to 59 years (vs 18 to 29 years), and those with underlying medical conditions, symptomatic infection, and/or hospitalization during infection were more likely to have long COVID-19 at 3 months. Symptomatic infection was linked to an estimated 13 times greater likelihood (adjusted odds ratio, 13.3) of developing long COVID. In contrast, participants aged 60 years and older and minority ethnicities were less likely to develop the condition.

Of the 1,510 long-COVID patients, 1 in 5 reported an impaired ability to perform daily activities, and at least 1 in 3 said their work was affected.

"As the symptoms cut across multiple organ systems, management of individuals affected by this condition will likely require, or benefit from, dynamic and coordinated cross-sectoral interventions involving multiple specialties," the study authors concluded.

• In an ongoing investigation into a recent measles cluster, the Philadelphia Department of Public Health (PDPH) has now confirmed five cases and has reported three suspected infections. In a January 5 update, the agency said three patients remain hospitalized. The initial patient was hospitalized in early December, which resulted in three confirmed cases in patients who weren't immune to the virus. One of the patients attended daycare on December 20 and 21, exposing children and staff. In a previous update, PDPH said the patient's caregivers had disregarded quarantine and exclusion instructions. Two children at the daycare tested positive, both of whom were hospitalized. Three other potential cases have been reported in kids from the daycare. Health officials continue to track potentially exposed people and are offering free measles, mumps, and rubella (MMR) vaccination at city health centers.
• South Sudan's health ministry recently reported a yellow fever outbreak, with one case confirmed so far. The patient is an 18-year-old man from Yambio County in Western Equatoria state in the southwest, according to a December 24 statement. His symptoms began on December 21, and after healthcare providers determined that his illness met the case definition for yellow fever, they isolated the man and collected a blood sample. Testing at the country's national lab and at the Uganda Virus Research Institute confirmed yellow fever. The South Sudan health ministry has activated the emergency operations center to coordinate the response and is conducting a field investigation with a team of experts from partner organizations. With World Health Organization support, the health ministry has applied for yellow fever vaccine doses from the global stockpile for campaigns in the affected region.
• A bombing today by militants in northwestern Pakistan near the Afghanistan border has killed five police officers who were in a truck on their way to guard polio vaccinators working on a campaign in a tribal area, the Straits Times reported today. The Pakistan Taliban has reportedly claimed responsibility for the bombing, part of a series of attacks ahead of Pakistan's February 8 national election. The attack also wounded 20 other officers. Pakistan is one of a few countries where wild poliovirus type 1 (WPV1) is still endemic, but extremist groups have targeted polio vaccination efforts due to suspicions that the immunizers are spies, and that the vaccine could make Muslims infertile.