Due to interest in reports of human metapneumovirus (hMPV) cases in China, the World Health Organization (WHO) today weighed in on respiratory infection activity in the Northern Hemisphere,  including the latest data from China.

Media reports have described a surge of respiratory virus activity in China, which included involvement of hMPV and strain on the country’s health system. The virus is one of many common viruses that causes human colds and is known to circulate alongside other winter-season viruses such as influenza and respiratory syncytial virus (RSV).

The WHO said flulike illness levels and acute respiratory infection rates have increased in some Northern Hemisphere countries in recent weeks and are above baseline levels. Flu remains elevated, while RSV activity is generally declining, except for in North America.

The group pointed out that not all countries test for and track hMPV, which is generally mild but can result in hospitalizations from bronchitis and pneumonia. 

Flu most common among China’s sick; no usual pattern seen

Data from China through December 29 show that acute respiratory illnesses increased in recent weeks, with detections of seasonal flu, rhinovirus, RSV, and hMPV, especially in the country’s northern provinces. The levels are within the range expected for this time of year, with influenza the most common cause so far.

The WHO said it is in contact with Chinese officials and that it has not received any reports of unusual outbreak patterns. “Chinese authorities report that the health care system is not overwhelmed and there have been no emergency declarations or responses triggered,” the WHO added.

France’s health ministry today reported the country’s first clade 1b mpox case, which involves a person from Brittany who hadn’t traveled abroad, but was in contact with two people who had returned from Central Africa.

In a statement, officials said an investigation is underway to determine how the patient contracted the virus and to identify others who may be at risk. They said the overall risk to the general public in France and Europe is low, but sporadic cases linked to outbreak countries may occur.

The case from France marks the eleventh country outside of Africa to detect clade 1 mpox, which is different than the clade 2 virus circulating globally. Most were imported cases linked to African travel, but detections in India, Pakistan, and Oman were related to travel to the United Arab Emirates.

Limited secondary transmission was reported in household index cases in the United Kingdom in October, and Germany in December.

Several African countries have been battling mpox outbreaks involving a mix of clades over the past year, with the Democratic Republic of the Congo (DRC) remaining the primary hot spot. The novel clade 1b is driving much of the activity in the DRC and has spread to a handful of other countries. The arrival of the new clade has some with broader transmission patterns, including household spread that has especially affected children.

A study today in Infection Control & Hospital Epidemiology of more than 44,000 COVID-19 cases in Los Angeles County nursing homes reveals that hospitalizations and deaths per 100 residents fell from 31 and 24, respectively, prior to widespread vaccination to 11 and 7, respectively, afterward from March 2020 to April 2022.

LA County has 383 nursing homes housing more than 35,000 licensed beds. County health officials documented all COVID-19 outbreaks beginning in March 2020. In total 44,279 cases were analyzed from 1,587 outbreaks in 313 nursing homes. The authors defined an outbreak as 1 or more cases in nursing home residents with lab-confirmed COVID-19 infection and no periods of 14 or more days between successive COVID-19 cases in residents. 

Biggest outbreaks during Omicron

Through the median outbreak size peaked during the 2021-22 winter, when the Omicron variant dominated COVID-19 transmission in the United States, severity dropped significantly, as most residents were vaccinated.

Despite peak or near-peak outbreak duration and size in the winter surge that followed vaccination, the decline in severe outcomes observed upon vaccine introduction endured.

"Despite peak or near-peak outbreak duration and size in the winter surge that followed vaccination, the decline in severe outcomes observed upon vaccine introduction endured," the authors wrote. 

They added, however, "Our study also adds to existing evidence that surges in community transmission are strongly correlated with the spread of SARS-CoV-2 in NHs [nursing homes] … even after widespread vaccine availability."

Eighty-seven percent of hospitalizations and 89% of resident deaths took place before widespread vaccination, or March 2020 through January 2021.

Among hospitalized preterm infants given their routine 2-month vaccinations, 24% had at least one apnea episode within 48 hours, compared with 10% of unvaccinated infants, but the average number and duration of the episodes didn't differ significantly between the groups, and there were no serious adverse events, concludes a randomized clinical trial published yesterday in JAMA Pediatrics.

The Duke University–led trial involved 223 6- to 12-week-old infants born before 33 weeks' gestation at three US neonatal intensive care units from August 2018 to October 2021. In total, 105 were vaccinated, and 116 were unvaccinated. Apnea was defined as a respiratory pause longer than 20 seconds or a pause longer than 15 seconds with less than 80 heartbeats per minute. 

Immunized infants were vaccinated against pneumococcal disease; diphtheria, tetanus, and acellular pertussis; hepatitis B; polio; and Haemophilus influenzae type b within 12 hours of randomization.

The perceived risk of post-vaccination apnea in preterm infants likely contributes to undervaccination in this group, the study authors said.

"Preterm infants are recommended to receive most vaccinations at the same postnatal age as term infants," they wrote. "Nonetheless, only half of infants discharged from the neonatal intensive care unit (NICU) after lengths of stay of 60 days or longer are fully vaccinated, and preterm infants have been shown to be underimmunized at older ages."

Findings support current vaccine guidance

The proportion of infants with one or more apnea event was 24% in the vaccinated group and 10% in the unvaccinated group (adjusted odds ratio, 2.70). The average number of episodes didn't differ significantly (model point estimate of difference, 0.54) between vaccinated (2.72) and unvaccinated (2.00) infants. Nor did the average length of episodes (model point estimate of difference, 4.6) between the groups (27.7 and 32.3, respectively). No serious adverse events occurred.

These findings support current recommendations to vaccinate most hospitalized preterm infants at 2 months’ chronological age; neonatal clinicians should continue to provide evidence-based anticipatory guidance about postvaccination apnea risk.

"These findings support current recommendations to vaccinate most hospitalized preterm infants at 2 months’ chronological age; neonatal clinicians should continue to provide evidence-based anticipatory guidance about postvaccination apnea risk," the researchers wrote.