COVID-19 Scan for Mar 25, 2021

News brief

Scientists report that SARS-CoV-2 infects oral cells

SARS-CoV-2, the virus that causes COVID-19, infects cells in the mouth, according to a study published today in Nature Medicine. This could change perceptions on how the virus travels to the lungs or the digestive system as well as how it is transmitted from person to person, the researchers write.

The investigators created a map of the mouth's tissues and found some salivary gland and gum cells were vulnerable to the virus because of their potential to create ACE2 and TMPRSS2 proteins, or the entry points of SARS-CoV-2 infection. To confirm their suspicions, they looked at 18 COVID-19 cadavers, of which 88.9% had the virus in their salivary glands. Infection was also found in two sets of tissues, affecting five of six mucosal sites.

In 39 living people with COVID-19, those who were asymptomatic (22%) were associated with a 1-week quicker average viral clearance time (range, 0.5 to 3.5 weeks) than that of symptomatic participants. In symptomatic patients, saliva infected with SARS-CoV-2 was associated with a 4.8-fold likelihood of altered taste and smell (95% confidence interval, 1.14 to 19.98).

After exposing saliva from eight people with asymptomatic COVID-19 to lab-grown cells, the researchers noted that infection occurred in 25%. Salivary glands appeared to have the ability to mount immune responses, though, as an analysis of the larger cohort showed immunoglobulin G antibodies against nucleocapsid antigens (73.3%, 22 of 30) and spike antigens (53.6%, 15 of 28), both of which were measured to 9 weeks post-COVID confirmation.

The researchers conclude, "Matched nasopharyngeal and saliva samples displayed distinct viral shedding dynamics, and salivary viral burden correlated with COVID-19 symptoms, including taste loss. Upon recovery, this asymptomatic cohort exhibited sustained salivary IgG antibodies against SARS-CoV-2."

"Our study could open up new investigative avenues leading to a better understanding of the course of infection and disease," lead author Blake M. Warner, DDS, PhD, MPH, said in a National Institutes of Health (NIH) and National Institute of Dental and Craniofacial Research (NIDCR) press release. "Such information could also inform interventions to combat the virus and alleviate oral symptoms of COVID-19."
Mar 25 Nat Med study
press release


B117 variant exhibits higher transmission rates

The B117 COVID-19 variant, which was first identified in the United Kingdom, may have a 50% to 100% higher reproduction rate, according to a study published in Nature today. This finding echoes recent studies such as a Science article published at the beginning of March.

The researchers looked at 31,390 B117 and 52,795 non-B117 whole-genome SARS-CoV-2 sequences with known time and location of collection from Oct 1, 2020, to Jan 16, 2021, as well as samples with S-gene target failure (SGTF) results from mid-November, when more than 97% of confirmed SGTFs indicated B117 lineage.

While the variant of concern (VOC) was originally concentrated in London (9,134), South East (5,609), and East England (4,413), the researchers say that, since Jan 16, it is widely distributed across the country and became the majority strain on Dec 3 The researchers also note that it affects a larger proportion of people under 20 than non-B117 strains do.

The additive growth rate differences between B117 and non-B117 strains was 0.69 per week (95% credible interval [CrI], 0.61 to 0.76), which peaked in November and then declined to 0.43 (95% CrI, 0.33 to 0.52) by the study's end. Further modeling suggested that the reproduction ratio of B117 to non-B117 strains is 1.89 (95% CrI, 1.43 to 2.65), and the researchers add that even if B117's generation time is actually half that of previous variants, the ratio lowers to only 1.53 (95% CrI, 1.27 to 1.79).

"Analysis of trends in SGTF and non-SGTF case numbers in local areas across England shows that the VOC has higher transmissibility than non-VOC lineages, even if the VOC has a different latent period or generation time," the researchers conclude.
Mar 25 Nature

CDC notes dramatic drop in HPV in females since vaccine introduced

Since the introduction of the human papillomavirus (HPV) vaccine in 2006, rates of HPV infections among females fell 88% in teens 14 to 19 years and by 81% in those aged 20 to 24 by 2018, according to a study today in Morbidity and Mortality Weekly Report (MMWR).

Vaccination against HPV, which is transmitted through sex, has been recommended for girls at age 11 or 12 years since 2006 and for boys since 2011 to prevent cervical, anogenital, and oropharyngeal cancers and anogenital warts. Catch-up vaccination is recommended for men and women through age 26.

The study, led by researchers from the Centers for Disease Control and Prevention (CDC), involved data from the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2006 (pre-vaccine), 2007 to 2010, and 2017 to 2018.

Among sexually experienced females, HPV prevalence fell in those who reported receiving at least one dose of vaccine (-97% among 14- to 19-year-olds, -86% among those 20 to 24), as well as in those who remained unvaccinated (-87% among those aged 14 to 19, -65% among those 20 to 24).

The authors said that the substantial decreases among unvaccinated females suggest herd effects and may be related to a decrease in reported sexual behaviors among those aged 14 to 19. "These find­ings suggest strong herd effects, or indirect protection of unvac­cinated females, as reported in previous NHANES analyses and in data from other countries," they wrote. "The herd effects are likely attributable to less circulation of vaccine-type HPV because of both female and male vaccination in the United States."

The decline in HPV infections was first noted in the 4 years after vaccine introduction in the 14- to 19-year age-group and within 6 years in the 20- to 24-year age-group. While vaccine uptake has increased, it remains lower than that of other vaccines recommended for adolescents, the researchers said.

A drop in HPV vaccination during the COVID-19 pandemic threatens to reverse gains made thus far in HPV vaccination coverage, the researchers added, and efforts must be made to increase vaccination and to continue monitoring of infection data.
Mar 25 MMWR study


Report calls for broader approach to STI prevention and control

Despite a sharp rise in US sexually transmitted infection (STI) rates the over the past 20 years, STI prevention and control efforts remain underfunded, stigmatized, and detached from efforts to promote overall health and well-being, according to a new report from the National Academies of Sciences, Engineering, and Medicine (NASEM).

The report, which was commissioned by the CDC, argues that the nation's response to STIs has mostly focused on individual risk factors and individual behavior change, an approach that has tended to fuel blame and stigma. On top of that, the CDC's STI funding has remained flat over the past two decades, with a 40% reduction in inflation-adjusted dollars.

To address the growing epidemics of chlamydia, gonorrhea, and syphilis and strengthen the response to all STIs, the report recommends that public health agencies adopt a holistic approach that focuses on sexual health in the context of broader health and well-being. It calls for the Department of Health and Human Services (HHS) and state governments to broaden access to STI treatment and prevention by making it available through multiple venues, including comprehensive sexual health clinics, pharmacies, and urgent care settings, and to provide no-cost care options for patients to close coverage gaps.

The report also recommends that the National Institutes of Health prioritize development of rapid diagnostics, new antimicrobials, and vaccines for STIs, calls for support and expansion of the STI workforce, urges the CDC to partner with parents, parent-teacher associations, and school boards to establish guidelines for school-based sexual health education, and recommends that the CDC leverage social media for STI prevention efforts.

"With the release of this report and the creation of the first-ever HHS STI National Strategic Plan in December 2020, we have many opportunities to address structural barriers to STI prevention and care, minimize exposure to STIs, and ensure that services are easily available in welcoming, stigma-free environments," Sten Vermund, MD, PhD, dean of the Yale School of Public Health and chair of the committee that wrote the report, said in a NASEM press release.
Mar 24 NASEM press release
Mar 24 NASEM STI report


Countdown starts for Guinea's Ebola outbreak

Guinea's last Ebola patient was discharged 2 days ago from a treatment center in N'Zerekore, which started the 42-day count down until the end of the country's latest Ebola outbreak, the World Health Organization (WHO) African regional office said today on Twitter.

The WHO added that the countdown started just 38 days after Guinea's outbreak began. The event marks Guinea's first since West Africa's massive outbreak between 2014 to 2016, and early genetic analysis suggests that the new flare-up was linked to that earlier outbreak, hinting at the possibility that the virus can persist in protected body sites such as the eyes or testes much longer than previously thought.

So far, Guinea has reported 18 cases, 9 of them fatal in the current outbreak. And nearly 4,000 people in the outbreak area have been vaccinated.

The latest announcement about Guinea's outbreak comes 2 days after the WHO announced that the last Ebola patient in the Democratic Republic of the Congo (DRC) left treatment, which began that country's countdown to the event being declared over.
Mar 25 WHO African regional office tweet
Mar 23 CIDRAP News scan "Countdown begins for end of DRC's Ebola outbreak"

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