It has been a couple of weeks since the last newsletter. Vaccine distribution in the U.S. continues to increase with approximately 112 million people having received at least one dose, and 66 million people fully immunized. Pockets of COVID-19 outbreaks are occurring in numerous states however Michigan is experiencing a significant outbreak with daily case numbers and hospitalizations nearing the pandemic peak in December. Most of these areas are also seeing a significant rise in B117 variant activity, which is thought to be the cause for the increasing cases. Unfortunately, this is a very concerning trend.
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1. B117, Should I be concerned?
B117 is the COVID-19 variant first detected in the United Kingdom. It was responsible for a large outbreak in the UK and shown to be more easily passed from person to person. It was also felt to result in more severe illness. In the US, the CDC reports that the variant has become the dominant strain in all samples tested. As the country passes 33% of the population having received at least one dose of a vaccine and 19% being fully vaccinated, we hope the effects of B117 will be less severe. All 3 currently authorized vaccines have shown the ability to produce antibodies that neutralize the B117 variant in small studies (Pfizer, Moderna, J&J ). If you have not been vaccinated, time is of the essence.
2. What about the other variants?
The US has largely seen B117 variant activity. The other two variants of concern listed by the CDC include the P1 (Brazil) and B1351 (South African) variants. Both have been identified in the US, but in small numbers so far. Three interesting studies were recently published about these variants:
The first was published in the Journal Nature, and studied the antibodies of those who recovered from B1351 versus those who recovered from other strains. Interestingly, they found that antibodies from those who recovered from B1351 (South African) variant infection were able to neutralize all other variants. However, antibodies from people who recovered from other strains were not able to neutralize the B1351 variant. The authors concluded that vaccines targeted against this variant may prove effective against all previous variants.
The second study published in the Journal Cell, studied the antibodies of recovered or vaccinated patients against the P1 (Brazil) strain in comparison to the B1351 variant. They found that the P1 variant was far less resistant to antibodies of recovered patients or those vaccinated with Pfizer or Astra Zeneca vaccines. They also found that P1 was susceptible to the antibody medications manufactured by Regeneron and Eli Lilly, much like the B117 variant.
The third study was performed by the National Institute of Health (NIH) and examined 30 people who had recovered from COVID-19 infection by the original strain of the virus. They found that the T cells in their blood samples were able to recognize multiple variants, including B117 (UK), B1351 (South Africa), and P1 (Brazil). This is good news that hopefully will be studied in larger numbers of patients.
3. What is happening with the Astra Zeneca vaccine ?
The Astra Zeneca / Oxford vaccine has unfortunately had a tumultuous course. It was studied and then widely used in the U.K.. Since that time, its use expanded in the European Union with concerns that there might be a link to rare clotting events. Initially, vaccine deployment was halted in the EU. After a brief period, the EU Medicine Authority found no cause for alarm and distribution was reinstituted. This past week both the EU Medicine Agency (EMA) and the U.K. Joint Committee on Vaccination and Immunization released statements discussing a possible link between the vaccine and two kinds of clotting problems. The EU Medicine Agency reported 62 case of cerebral venous thrombosis (CVT, clotting of a venous channel around the brain) and 24 cases of splanchnic vein thrombosis (SVT, clotting of a vein in the abdomen). Both conditions are known to be rare. CVT is thought to occur at a rate of 5 per 1,000,000 and SVT is thought to occur at a rate of 1-4 per 1,000,000. The EMA cited a rate of 1 per 100,000 for CVT and SVT combined. The 86 cases were associated with low platelet counts leading the EMA to speculate that the condition may be immune mediated. Of the 86 cases, 18 people died. The UK Joint Committee on Vaccination and Immunization has recommended this vaccine not be given to people under age 30, since this population has a very low rate of COVID-19 related hospitalization and death. Instead, they recommend an alternate vaccine be given. The EMA concluded “COVID-19 is associated with a risk of hospitalization and death. The reported combination of blood clots and low blood platelets is very rare, and the overall benefits of the vaccine in preventing COVID-19 outweigh the risks of side effects.” To date, over 25 million people in the EU and UK have received the vaccine.
4. Is it necessary to receive both doses of the Pfizer or Moderna vaccines?
This is a complicated question. The Pfizer and Moderna vaccines were studied as a two shot series. All the initial data is based on patients receiving both doses. After two doses, these vaccines show an efficacy of >95% against severe COVID and 100% against death. Recently, the CDC published data examining the effectiveness of the vaccines in healthcare workers and first responders. After examining 3950 workers, they concluded that the Pfizer and Moderna vaccines were 80% effective >14 days after the first dose, and more than 90% effective >14 days after the second dose. Though this study was published last week, other studies have reached similar conclusions leading the UK to vaccinate as many people as possible with one dose while delaying the second dose up to 12 weeks. In addition, there is good evidence from multiple antibody studies showing that people who have recovered from COVID-19 have an antibody response to one vaccine dose that is more robust than someone who has never had COVID after two doses of vaccine. Also, one study (journal Science) found that recovered patients benefit from one dose of vaccine because it broadens their immune response to other variants. So currently, the best answer is this:
- If you have recovered from COVID-19 infection, you are well protected after one dose of any vaccine.
- If you have never been infected with COVID-19 but are at high risk of severe illness, you should receive both doses.
- If you have never been infected with COVID-19 but are at low risk of severe illness, one dose if likely to be very effective. Completing the full course, if possible, is still beneficial.
5. What is the debate surrounding rapid testing? Is it reliable?
Testing for COVID-19 infection at the start of the pandemic was PCR only. This test would take up to several days to return a result and there were few labs able to process the test, performed on a nasal swab specimen. As the pandemic progressed and technology improved, manufacturers developed rapid molecular tests able to detect the same genetic material of the virus but in shorter time frames than traditional PCR tests. These tests are just as accurate. However, manufacturers also developed rapid tests called “rapid antigen” tests based on the same technology we currently use for rapid strep and flu tests. These rapid antigen tests detect proteins not the RNA of the virus. They are less reliable and prone to error. This has led to debate about the wide use of the tests. Some advocate for easy access to rapid testing everywhere in order to quickly identify new cases, while others are concerned this will provide a large number of erroneous results and expose people who would otherwise be in isolation.
A recent study compared three commercially available rapid tests with the standard PCR test. They found that rapid antigen tests were half as sensitive, but had a low risk of false negatives when used correctly in people who had high viral loads. These are patients who are symptomatic at the time of the test. The tests did not perform well in people who had no symptoms.
Meanwhile, the FDA has approved three rapid antigen tests for use in “serial screening” without a prescription. These tests were previously authorized for use in healthcare settings, but the FDA notes they may now be used for “testing asymptomatic individuals multiple times on a routine basis“. Though the tests are less accurate than PCR testing, when used multiple times on the same person during regular screening, the error rate is thought to be lower.
So yes, rapid antigen tests ARE less reliable. However, in people who are symptomatic or in regular screening of asymptomatic people, they can be of benefit. PCR testing remains the most reliable method of virus detection and identification of infected individuals. This has led some healthcare settings to obtain both tests simultaneously- a rapid and a PCR for confirmation. This is a good practice, but requires knowledge of the tests and patient symptoms in order to interpret results that may conflict.
6. How long am I immune after receiving a vaccine or recovering from COVID-19?
The original vaccine studies for Pfizer and Moderna were conducted in late 2020. That means we have less than 1 year of data from trial participants. However, we do know that those participants have had persistent protection against COVID. Pfizer released a statement from its continued surveillance of its trial participants. It noted that participants have had 6 months of successful protection against COVID and without any serious safety concerns. A study published in the New England Journal of Medicine found the same protection (6 months) for recipients of the Moderna vaccine. The full duration of protection is unknown, but surveillance will continue of all trial participants.
For those who have recovered from COVID-19, immunity has also demonstrated long lasting effects. The National Institute of Health (NIH) published a study in January showing that there was persistent immunity up to 8 months, which was the duration of the study. Also, a more recent study published in Frontiers Immunology looked at T-Cell immunity and found levels to be detectable up to 5 months after recovery. However, there is one caveat for recovered patients: variants. Unfortunately, we do not know if recovery from infection provides protection against all other variants. As discussed in item 4 above, there may be benefit in vaccinating recoverees with a single dose of COVID vaccine in order to provide more broad protection against variants. More study is necessary.
7. Does cleaning surfaces really prevent infection with COVID-19?
This week the CDC revised its recommendation on disinfecting surfaces against SARS-CoV-2. In doing so, the CDC reinforces what has been suspected for some time, that COVID-19 is primarily transmitted by infected people through the air and not by infected surfaces. The new guidelines suggest that once daily disinfection is sufficient unless there has been a known case of COVID-19 in the area. It also states that the risk of transmission by surfaces is low. Lastly, it suggests that regular cleaning is sufficient in most cases and that chemical disinfection is not necessary regularly. There are certainly nuances to the recommendations, and the CDC states “This guidance is indicated for buildings in community settings and is not intended for healthcare settings or for other facilities where specific regulations or practices for cleaning and disinfection may apply.”