Over the last week, MLive received a number of questions related to natural immunity from prior coronavirus infection and how it compares to immunity initiated by a vaccine.
It’s still too early to fully understand the varying levels of immunity against coronavirus, but the scientific community is slowly piecing together the puzzle using various clinical and real-world studies.
Natural immunity “does provide pretty good protection, there’s no doubt about that,” Dr. Liam Sullivan, a Grand Rapids infectious disease specialist with Spectrum Health, told MLive earlier this fall. “The question is how long does that protection last, and I think it’s too early to say.”
Why should previously infected people get vaccinated? The oversimplified answer is this: Doing so offers very little downside, but could further your protection against the different coronavirus variants, and extend the duration of immunity.
A recent study from Israel did suggest that natural immunity can be more protective against the delta variant than two doses of the Pfizer vaccine. The study compared 16,125 Israelis who were vaccinated in January or February to 16,125 infected with SARS-CoV-2 during that time, and looked at the number of breakthrough cases and reinfections from June 1 to Aug. 14.
However, immunity can vary by strain of coronavirus. Another study from Brazil found antibody effectiveness was six times weaker against the P.1 strain compared to the original SARS-CoV-2 strains, and thus 25% to 61% of previously infected people were susceptible to infection with the P.1 strain.
So, immunity from older strains of coronavirus don’t necessarily mean protection against new variants, whereas vaccines seem to be more consistent in dealing with mutant strains.
“Many people, and many doctors, are assuming that any prior exposure to SARS-CoV-2 will confer immunity to re-infection. Based on this logic, some people with prior exposure don’t think they need to get vaccinated. Or if they do get vaccinated, they think that they only need the first dose of the two-dose Pfizer/Moderna vaccines,” Thomas McCade, a biological anthropologist who was part of the team that conducted the study, said in a press release.
“Our study shows that prior exposure to SARS-CoV-2 does not guarantee a high level of antibodies, nor does it guarantee a robust antibody response to the first vaccine dose. For people who had mild or asymptomatic infections, their antibody response to vaccination is essentially the same as it is for people who have not been previously exposed.”
A few readers asked MLive if Michigan was close to a level of herd immunity if you combine those who have been vaccinated and those with a prior infection. As of about a month ago, health officials estimated about 68% of the state’s residents had some level of protection against COVID-19.
How did they come up with that?
As of early September, 55.6% of all Michiganders had received at least one dose of vaccine and an estimated 28% had been previously infected with coronavirus based on antibody testing data. The University of Michigan’s School of Public Health developed a model that combined that data, and assumed that people were equally likely to get vaccinated whether they had been previously infected or not.
That estimate has likely only inched up by mid-October, because new vaccinations remain low. Weekly vaccinations over the last two weeks are the lowest since the first week shots were available in December 2020.
Health officials would like to see immunity rates reach 80% to 90%, so it’s not yet believed that Michigan as a community has reached a level of herd immunity to protect those unable to get vaccinated.
Below are some of the additional COVID-19 inquiries MLive received over the last week. A number of questions received this week were already answered in last week’s Q&A, which can be found, here.
If you have a question, send it to email@example.com. Our public health team will answer and perhaps feature it in an upcoming story.
Q: Where can I get a COVID test and how much does it cost? Can uninsured people get a test for free?
The state has an online COVID-19 test finder — available here — that lets you put in your location to see what options you have in your area. You can also call the COVID-19 Hotline at 888-535-6136, and press 2 for help finding a test site.
Costs for tests vary by provider and whether the test provides rapid results or requires more than a 24-hour wait. While using the online test finder, there is a drop-down menu to specifically select no-cost locations, which use grant money to cover the cost of tests for those who don’t provide insurance information.
However, be sure to verify that there are no costs associated with the testing process when you sign-up. Some providers will come up as “no-cost” because they won’t charge you for the test, but they will charge you for a brief virtual check-up before the test. Confirm the costs before booking your appointment.
Additionally, at-home tests are available at some pharmacy locations. Due to high demand, they may be difficult to find, though there is expected to be an increase in supply in the near future.
Q: How many days before I showed symptoms was I infected with the coronavirus?
Symptoms from COVID-19 can develop 2-14 days after exposure to the virus, according to the CDC. So a symptomatic patient could have been exposed up to two weeks before they began feeling ill, but the average was less than a week pre-delta variant, and it’s gotten shorter with the delta variant.
Q: My son was vaccinated at the beginning of the pandemic but just tested positive for coronavirus. Is his isolation the same and what is the isolation period for others who are vaccinated and were near him the day before he tested?
The CDC recommends a 10-day isolation period for COVID-19, with the clock starting the day symptoms appeared or the day your specimen was collected for testing — whichever came first. That remains true for re-infection cases and for people who are vaccinated.
If you’re vaccinated and have a close contact with someone who tests positive, you don’t have to immediately isolate for 10 days, but it is recommended that you get tested 3-5 days after your exposure, and that you wear a mask indoors for up to two weeks or until you get a negative test result.
On the bright side, there are some studies that indicate fully vaccinated people clear the virus from their systems faster than non-vaccinated people.
Q: Two hours after my booster shot I got sick with diarrhea, nausea and chills. Is this a normal reaction?
Among the most common side effects after a second or third dose of the Pfizer or Moderna vaccines are nausea, chills, fever, tiredness, headache and muscle pain. Those reactions can be signs of the body building protection against future infections. They can occur hours after the shot and typically last up to a few days.
While two hours is on the quicker side, it’s not out of the ordinary. It’s also possible that you were already infected with something and the timing was coincidental. However, you shouldn’t be concerned as long as your symptoms improve over a few days.
The CDC recommends contacting your health care provider if your side effects don’t seem to be going away after a few days, or if the redness or tenderness at the injection shot gets worse after 24 hours.
Q: I have received both of my COVID vaccine doses. If I were to come into contact with one of the variants but was asymptomatic would I be at risk of unknowingly transmitting COVID to non-vaccinated people?
Fully vaccinated people can become infected with coronavirus, and are more likely to be infected with the delta variant than previous, less-infectious strains. They are also less likely than a non-vaccinated person to become infected in the first place.
As for asymptomatic spread, there is evidence that infected individuals can spread coronavirus to others without displaying any symptoms. The CDC published an analysis earlier this year that found the viral loads in people infected with the delta variant were similar among vaccinated and unvaccinated people.
Q: If a whole household gets sick is the person that got symptoms first the spreader?
This simple answer is, no, not necessarily. Two people in a household could get sick a day or two apart and have been exposed to the same source. One person could have been infected earlier and developed symptoms on the longer end of the CDC’s 2-14 day window, while another could be infected later and develop symptoms on the shorter end.
The delta variant also comes with a shorter incubation period, meaning the virus needs less time than prior strains before symptoms develop.
Q: How many vaccinated people in Michigan have died from COVID-19? How many deaths have been attributed to the vaccine, and what percentage of all reported cases are vaccinated?
Between Jan. 15 and Sept. 28, there were nearly 4.89 million people fully vaccinated against COVID-19 in Michigan. Among that population:
- 32,802 people tested positive for COVID-19, or 0.67%;
- 1,296 people were hospitalized for COVID-19, or 0.027%;
- 488 people died of COVID-19, or 0.0010%.
Meanwhile, there were 488,965 cases in unvaccinated people, resulting in 13,279 hospitalizations and 5,545 deaths during that stretch.
As for deaths attributed to the vaccine itself, there have been four throughout the U.S. — none in Michigan — all attributed to a rare but serious blood clotting condition known as “thrombosis with thrombocytopenia syndrome” and linked to the Johnson & Johnson vaccine.
There have been other reported cases among individuals who received a COVID-19 vaccine days or weeks before their death, but the official cause of death has not been linked to the vaccine. As an important reminder, the public database known as the Vaccine Adverse Event Reporting System (VAERS) includes reports of additional deaths following a vaccine, but the data can be misleading.
Health officials and VAERS itself warn that the database is prone to bias and doesn’t provide an accurate picture of vaccine side effects. Anyone can submit a report, and VAERS accepts all reports without determining whether adverse effects were actually caused by vaccines.
If you have a COVID-19 related question as we continue through this pandemic, please respectfully submit it to firstname.lastname@example.org.
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