Weekly Covid-19 Update: Tuesday, December 21, 2021

Happy Tuesday, everyone. In this week’s update I have much more information on Omicron, the symptoms of Omicron, findings out of South Africa where Omicron caused a massive fourth wave of Covid, more info on vaccines, and a study on an antiviral drug. In the past I’ve been very careful to include a majority of peer-reviewed research articles in these updates, but due to the fast-moving nature of Omicron most of the research below has not had adequate time to undergo peer review, so please note that most of these findings are preliminary and still need to go through that very important process.

1) Researchers at the University of Hong Kong studied the Omicron, Delta, and original Covid-19 variants to understand how they affected the human bronchi (large tubes in your chest that carry air to your lungs) and the lungs. Findings showed that Omicron replicated approximately 70 times faster in the bronchi than either the Delta or original Covid (which could explain why it seems to spread more quickly than previous variants), but it replicated more than 10 times slower in human lung tissue. This may suggest that the Omicron variant is less severe than previous variants, although this obviously needs to be confirmed in follow-up studies. The paper is currently under peer review for publication and a summary of the study can be found here: https://www.med.hku.hk/en/news/press/20211215-omicron-sars-cov-2-infection

2) In case you haven’t yet seen a list of symptoms for Omicron, an article published in the British Medical Journal (BMJ) outlined the top five symptoms based on Omicron cases in the UK. They include runny nose, headache, fatigue (mild or severe), sneezing, and sore throat. Another report out of South Africa based on data from 78,000 confirmed Omicron infections said that the most common early signs of Omicron were a scratchy throat, nasal congestion, a dry cough, and myalgia manifesting in lower back pain. You can read the BMJ article here: https://www.bmj.com/content/375/bmj.n3103 and a news article about the South African findings here: https://www.telegraph.co.uk/global-health/science-and-disease/lower-back-pain-scratchy-throat-emerge-symptoms-omicron/

3) In another study by South Africa’s Discovery Health based on 211,000 confirmed Omicron cases, researchers found that two doses of the Pfizer vaccine provided just 33% protection against infection from Omicron, but 70% protection against hospitalization. This protection against hospitalization was true for all age groups over 18 as well as those with comorbidities such as diabetes, hypertension, and other cardiovascular diseases. The research also found that for those who previously had Covid, the risk of reinfection with Omicron was significantly higher than with previous variants. For those who had been infected with Delta, the risk of reinfection was 40% and for those with the Beta variant (also known at the time as the “South African variant”) the risk was 60%. Next, the study reported that Omicron spreads much more quickly, but resulted in fewer cases of severe disease and hospitalizations than previous variants (which could be due to high levels of previous infection and vaccinations; everything I’ve read indicates it is too early to say it is definitely less severe). Finally, amongst children the findings showed that “children under age 18 have a 20% higher risk of admission for complications of COVID-19 when infected with Omicron”. You can read the full report here: https://www.discovery.co.za/corporate/news-room

4) A new study published in The Lancet studied the AstraZeneca and Pfizer two-dose vaccines against the original Covid strain (known as “Victoria”), as well as the Beta, Delta, and Omicron variants. Findings showed a significant decrease in efficacy for both vaccines against Omicron, especially in the AstraZeneca vaccine, where all but one study participant’s neutralizing titres dropped below the threshold for detection (in layman’s terms, two doses of the AZ vaccine did not work against Omicron). The authors noted that there is likely to be an increase in breakthrough infections in individuals who have only received two doses of a vaccine, which could drive a new wave of infection. This seems to point to the findings of several studies from last week’s write-up, which stressed the importance of booster doses. You can read the full report here: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02844-0/fulltext

5) Speaking of boosters, yesterday Moderna announced the results of tests using its vaccine as a booster. In the small-scale study, several different dosage levels were tested in groups of 20 people. By day 29 after receiving the booster, the 50-microgram dose and 100-microgram dose groups both experienced sharp increases in neutralizing antibodies against Omicron (37-fold and 80-fold, respectively). The company now plans to expand its study using up to 600 participants. The data from this study has not yet undergone peer review. You can read more about it via this article from Reuters: https://www.reuters.com/business/healthcare-pharmaceuticals/moderna-says-booster-dose-its-covid-19-vaccine-appears-protective-vs-omicron-2021-12-20/ and this article from the New York Times: https://www.nytimes.com/2021/12/20/health/moderna-covid-booster-omicron.html?referringSource=articleShare

6) In other vaccine news, Pfizer recently announced the results of their Phase II/III trial in children aged 6 months to 5 years. While the vaccines were shown to be safe with no severe events in the trial participants, the dosage used was only found to be effective in children between 6 months and under 2 years old. As the dosage was not effective in those ages 2–5, Pfizer is now testing a third dose of the vaccine equal to the one received in the first two doses rather than testing a higher dose. If this is successful they will seek authorization to use a three-dose vaccine series sometime in the first half of 2022. You can read Pfizer’s press release about it here: https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-provide-update-ongoing-studies-covid-19 and an insightful piece by epidemiologist Dr. Katelyn Jetelina here: https://yourlocalepidemiologist.substack.com/p/why-did-the-pfizer-young-kids-trial

7) In Covid treatment news, a peer-reviewed study published in The New England Journal of Medicine reported the results of a phase 3, double-blind, randomized, placebo-controlled trial of an antiviral drug called molnupiravir, developed by drugmaker Merck. They tested the drug on nonhospitalized, unvaccinated adults with at least one risk factor for severe Covid within 5 days of the onset of symptoms. Of the participants, 716 received the drug and 717 received a placebo. The risks of both hospitalization and death were lower in the group that received molnupiravir. The researchers concluded that the drug was effective and safe for this population. You can read the full study here: https://www.nejm.org/doi/full/10.1056/NEJMoa2116044?query=featured_coronavirus

8) Now for your world update. In the US, Omicron has become the dominant variant. (Side note — to my US friends, take it from those of us in the UK, this thing travels FAST and even boosters aren’t a fool proof way of avoiding it. We found that out in my household today!) Yesterday the US had 276,389 new cases, but the 14-day average is 143,164, which is a 20% increase over the past two weeks. Hospitalizations are up 14% and deaths have increased 3%. The top 10 states in terms of infections per capita include Rhode Island, New Hampshire, New York, Ohio, Illinois, Massachusetts, New Jersey, Delaware, Wisconsin, and Vermont (Indiana, you’re number 11). Today President Biden announced he will make 500 million rapid tests free for the public beginning in January. Another side note — we have had access to free rapid tests in the UK for quite some time and I can say they are VERY useful!
— In the UK Omicron continues to surge, as there were 90,629 new cases today and over the past two weeks there has been a 78% increase in cases. London is the current hot spot per capita with a 269% increase in cases over the past 14 days. The booster vaccine rollout continues to go well with 897,979 doses administered today. Tonight Prime Minister Boris Johnson announced there would be no new Covid restrictions prior to Christmas.
— Elsewhere, New Zealand has delayed its border opening until the end of February due to concerns about Omicron, and in Australia the state of New South Wales recorded its highest ever single-day case number at 3,057. Portugal ordered nightclubs and bars to shut down, announced that people should work from home from at least December 26 — January 9, and are limiting New Year’s Eve celebrations to no more than 10 people per group outdoors to help control the spread of Covid. Sweden also urged people to work from home and is requiring seated-only service at bars, restaurants and large public events.
US numbers: https://www.nytimes.com/interactive/2021/us/covid-cases.html
UK numbers: https://www.nytimes.com/interactive/2021/world/united-kingdom-covid-cases.html and https://www.bbc.co.uk/news/uk-51768274
NZ & AUS info: https://edition.cnn.com/world/live-news/omicron-variant-coronavirus-news-12-20-21-intl/index.html
Portugal and Sweden: https://www.theguardian.com/world/live/2021/dec/21/covid-news-live-who-declares-2022-to-be-the-year-we-end-the-pandemic-as-us-says-omicron-is-now-dominant-strain?filterKeyEvents=false&page=with:block-61c1d9648f08d3319b5d7ed0#block-61c1d9648f08d3319b5d7ed0

That’s all for this week. Merry Christmas to those of you who celebrate and I hope everyone stays safe and tests negative this holiday season! I’ll be back with another update next Tuesday.




Weekly wrap-up of the latest Coronavirus research and news for those who want a one-stop shop for peer-reviewed research findings written in a way that is easy to understand.

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Andrea Geurin

Andrea Geurin

Social scientist with a Ph.D. and a journalism background.

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