Weekly Covid-19 Update: Tuesday, October 5, 2021

Happy Tuesday, everyone. Here is the latest in Covid-related research. This week I’ve got information on the effectiveness of mask requirements in schools, pregnancy and the Delta variant, antibodies in breast milk, smokers and Covid, autoantibodies, long Covid, Merck’s new Covid drug, and of course a world update.

1. Two recent studies examined mask mandates in US schools. Not surprisingly, both studies found much lower rates of Covid-19 in schools with strict mask mandates. The first study assessed 520 US counties with clear mask policies (either a policy where everyone had to wear a mask or one in which no one had to wear a mask). Counties without school mask requirements experienced larger increases in pediatric Covid-19 cases than those with school mask requirements (34.85 cases per 100K people compared to 16.32 cases). The second study looked at 1,020 public schools in Arizona. Out of 191 Covid outbreaks during the study’s month and a half time period, 59% were in schools without mask requirements, compared to 8.4% in schools with early mask requirements. Those schools with no mask requirement were 3.5 times more likely to have outbreaks compared to schools with mask requirements. The study’s authors concluded, “Given the high transmissibility of the SARS-CoV-2 B.1.617.2 (Delta) variant, universal masking, in addition to vaccination of all eligible students, staff members, and faculty and implementation of other prevention measures, remains essential to COVID-19 prevention in K–12 settings.” Both studies were published in the CDC’s MMWR and can be read at the links below.
   Study 1: https://www.cdc.gov/mmwr/volumes/70/wr/mm7039e3.htm?s_cid=mm7039e3_e&ACSTrackingID=USCDC_921-DM66537&ACSTrackingLabel=MMWR%20Early%20Release%20-%20Vol.%2070%2C%20September%2024%2C%202021&deliveryName=USCDC_921-DM66537
   Study 2: https://www.cdc.gov/mmwr/volumes/70/wr/mm7039e1.htm?s_cid=mm7039e1_e&ACSTrackingID=USCDC_921-DM66537&ACSTrackingLabel=MMWR%20Early%20Release%20-%20Vol.%2070%2C%20September%2024%2C%202021&deliveryName=USCDC_921-DM66537
2. A peer-reviewed study published in the American Journal of Obstetrics and Gynecology examined 1,515 pregnant women infected with the Delta variant of Covid-19 between May and September 2021. Of those, 82 women developed severe Covid, 81 of whom were unvaccinated. Of those, 10 required ventilation and two died. The rate of infection and proportion of severe or critical cases increased significantly with the Delta variant compared to previous variants. The authors concluded, “Increased morbidity was observed in pregnancy with COVID-19 during the recent surge associated with the Delta variant, particularly in an underserved pregnant population where vaccine acceptance is low.” They stressed the need for pregnant women to be vaccinated. You can read the full study here: https://www.sciencedirect.com/science/article/pii/S000293782101005X
3. Previous research found antibodies in the breast milk of women who had recovered from Covid, but scientists were unsure whether these antibodies would help protect babies against the virus. A new study took breast milk samples from 75 women who had recovered from Covid-19 and found IgA antibodies in 88% of the sample. These antibodies were shown to neutralize the virus, or block infection. The researchers found that these antibodies can remain in the milk for up to 10 months. A second study also examined the milk of women who were vaccinated and found coronavirus-specific IgG antibodies in 100% of the women who received the Moderna vaccine (71% had virus-specific IgA antibodies), 87% of those who received Pfizer (51% had IgA), and 38% of those who received J&J (21% had IgA). Both of these studies are still undergoing peer review (important disclaimer!), but the pre-prints of each study can be found at the links below.
   Study 1: https://www.medrxiv.org/content/10.1101/2021.03.16.21253731v1
   Study 2: https://www.medrxiv.org/content/10.1101/2021.07.19.21260794v1.full.pdf
4. Using data from 421,469 individuals in the UK, researchers found that people who smoke were 80% more likely to be hospitalized due to Covid-19 than non-smokers and also had a significantly higher risk of death. The researchers reported that their findings “support a causal effect of smoking on COVID-19 severity”, meaning that they were confident smoking causes more severe cases of Covid-19. The study was peer-reviewed and published in the BMJ journal Thorax. You can read the full text here: https://thorax.bmj.com/content/early/2021/09/12/thoraxjnl-2021-217080
5. I’ve written about autoantibodies being discovered in the blood of patients with severe Covid-19 in the past. A new study involving 147 patients with severe Covid found these autoantibodies in approximately 50% of the patients. The researchers took blood samples for the patients at different time periods, including the day they were first hospitalized. Findings showed that approximately 20% of patients developed new autoantibodies within a week of hospitalization. In a press release about the study, which was published in the peer-reviewed journal Nature Communications, the lead researcher Dr Paul Utz of Stanford University said that the levels of autoantibodies seen in these patients were similar to those found in diagnosed autoimmune diseases and it is possible these patients could go on to develop autoimmune diseases in the future, but long-term research is necessary to determine this. The study concluded, “While the COVID-19 pandemic is leaving a wake of destruction as it progresses, it also provides an unprecedented opportunity to understand how exposure to a new virus could potentially break tolerance to self, potentially giving rise to autoimmunity and other chronic, immune-mediated, diseases.” You can read the full study here: https://www.nature.com/articles/s41467–021–25509–3
   And the press release here: https://med.stanford.edu/news/all-news/2021/09/covid-19-autoantibodies.html
6. One thing I often wrote in the early days of the pandemic and the early days of these research updates was something along the lines of, “There is still so much we don’t know about the long-term effects of this virus.” Indeed, we are still learning. New research on long Covid showed that out of 273,618 Covid survivors, 36.55% had at least one symptom of long Covid between 3–6 months after testing positive. Out of all Covid survivors, anxiety and/or depression was the most common symptom experienced during the 3–6 month post-Covid time period (15%), followed by abnormal breathing (8%), abdominal symptoms (8%), other pain (7%), chest/throat pain (6%), fatigue (6%), and headache (5%). The researchers found that the risk of long Covid was higher in patients who had more severe cases, it was slightly higher among females, and there were no differences based on race. The study was peer-reviewed and published in the journal PLOS Medicine and can be read in full here: https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003773
7. In additional long Covid news, new research in the UK showed that 12.3% of English secondary school students (equivalent to junior high and high school for my US readers) and 35.7% of school staff members reported ongoing Covid symptoms at least four weeks after initially testing positive. The most common symptom was weakness/tiredness for both staff (59.6%) and students (46.3%), followed by shortness of breath for staff (41.8%) and loss of smell for students (37.0%). Of those who experienced long Covid symptoms, 15.5% of the staff members and 9.4% of the students said their ability to carry out day-to-day activities was significantly reduced. The data were reported by the Office of National Statistics and the full report can be read here: https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/bulletins/covid19schoolsinfectionsurveyenglandprevalenceofongoingsymptomsfollowingcoronaviruscovid19infectioninschoolpupilsandstaff/july2021
8. Since the start of the pandemic there have been questions about how the virus originated. While some believed it could have been man-made in a laboratory, recent research found three coronaviruses in bats living in caves in Laos that add “substantial weight to existing evidence that the virus was not engineered” according to an article from Science. The three viruses are the closest relatives to SARS-CoV-2 (Covid-19) that have been found to date. One of the newly discovered coronaviruses is 96.8% identical in its genetic sequence to Covid, while another one is 96.2% identical. It is very important to note that the study is currently under peer review at the journal Nature Portfolio, so it has not yet been accepted by a peer-reviewed journal. You can read the full text of the pre-print here: https://www.researchsquare.com/article/rs-871965/v1
9. Pharmaceutical company Merck announced that it has developed an experimental antiviral pill that could halve the chances of death or hospitalization from Covid-19. The company’s results involved data from 775 Covid patients who were not hospitalized. They all joined the study within five days of developing symptoms and all had at least one risk factor for severe Covid. This drug is “the first oral antiviral that has proved to be effective against SARS-CoV-2” according to an article from Science. Merck plans to apply to the US Food and Drug Administration for emergency use authorization. In previous research the drug was shown not to be effective in patients who were already hospitalized. You can read an article about the drug here: https://www.science.org/content/article/unquestionably-game-changer-antiviral-pill-cuts-covid-19-hospitalization-risk
10. Now for your world update. In the US, the daily number of new cases has decreased 24% over the last two weeks. The current average number of new cases per day is 103,785. Hospitalizations have decreased 20% over the past two weeks and deaths have decreased 12%. Of those who are eligible for a vaccine (age 12+), 66% of people in the US are fully vaccinated. In the 65+ age group that number is 84%. State trends show that Alaska, Montana, North Dakota, West Virginia, and Wyoming have the most cases per capita, while Connecticut, California, Louisiana, Hawaii, and New Jersey have the fewest cases per capita.
    — In the UK the number of daily new cases has increased 12% over the past two weeks. The current average number of new daily cases is 33,317. Deaths have decreased by 21% over the past two weeks. In England, 90% of people age 16+ have received a first vaccine dose and 82% have been fully vaccinated. Currently there are over 100,000 children in England who are out of school with confirmed Covid cases.
    — Elsewhere, Australia has announced it will open its borders when 80% of the population aged 16 and older has been vaccinated, but the priority will be on bringing skilled migrants and students into the country. The Prime Minister indicated that international travel visitors would likely not be welcomed into Australia until 2022. Meanwhile, New Zealand announced it will abandon its zero-Covid strategy and instead learn to live with the virus. Only 49% of the NZ population is fully vaccinated, while 79% have received one dose. Both Portugal and Norway announced today that they would begin giving booster vaccines to everyone over the age of 65. Portugal currently has the world’s highest vaccination rate with 85% of its population fully vaccinated.
    Sources
    US data: https://www.nytimes.com/interactive/2021/us/covid-cases.html
    UK data: https://www.nytimes.com/interactive/2021/world/united-kingdom-covid-cases.html
    England vaccinations: https://www.bbc.co.uk/news/health-55274833
    Australia travel: https://abcnews.go.com/Health/wireStory/australia-international-tourists-2022-80406703
    New Zealand: https://edition.cnn.com/2021/10/05/asia/new-zealand-ardern-covid-zero-intl-hnk/index.html
    Other world updates: https://www.theguardian.com/world/live/2021/oct/05/coronavirus-live-news-california-deploys-national-guard-pfizer-jab-highly-effective-against-hospitalisations?page=with:block-615c41138f084fb3bf98d742#block-615c41138f084fb3bf98d742

That’s all for this week. If you made it this far, thanks for sticking with me. I realize this was a long update!