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Podcast 121: How Different COVID Vaccines and Doses Affect Heart Rate, Sleep, Fatigue & More

April 27, 2021

On this episode of our podcast, VP of Data Science and Research Emily Capodilupo breaks down the effects we’ve seen in WHOOP data from the various COVID-19 vaccines, and how the second doses impact people differently than the first. We also share highlights from an in-app AMA with Emily answering questions on the subject.

By Will Ahmed

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Emily Capodilupo, WHOOP VP of Data Science and Research, returns to the WHOOP Podcast to detail our latest COVID-19 vaccine research.

This research indicates that younger people are more likely to be affected by the vaccine than older people. Additionally, our findings show that you should expect to feel more rundown by the second dose of the Pfizer and Moderna vaccines than the first. The single shot Johnson & Johnson vaccine, meanwhile, looks similar in the data to the second dose of Moderna.

We’ve also seen that the vaccines can temporarily elevate your resting heart rate, lower your heart rate variability (HRV), and reduce the amount of restorative sleep you get. These aftereffects are short-lived, as WHOOP members who did experience a change in their physiological metrics returned to baseline quickly, often 24 hours after the shot.

Our full research on the subject is pending peer review and is available here in preprint.


COVID Vaccines & Doses Impact on Heart Rate Data: Podcast Show Notes

0:55 – Our Research. “We’ve had 51,000 doses reported by WHOOP members and we have looked at how that data is affecting your body,” Will says. WHOOP tracked how four different vaccines (Pfizer, Moderna, Johnson & Johnson, and Europe’s AstraZeneca vaccine) are affecting people. We also examined the differences in our data between when people get their first shots and second shots, how different age groups are handling the vaccines, what symptoms are most commonly reported post-shot, and how the vaccines are altering sleep patterns.

4:19 – Differences Between mRNA & Viral Vector Vaccines. The Pfizer and Moderna shots use mRNA (Messenger RNA), a new type of vaccine that teaches our cells how to make a protein that triggers an immune response inside our bodies. The Johnson & Johnson shot is a viral vector vaccine. These vaccines, which have been around since the 70s, use a modified version of a different virus to teach our cells how to fight the virus. Here’s more on how vaccines work.

6:30 – Key Takeaways. “What we’ve seen in the WHOOP data is very consistent with what you’ve probably heard on the news. For both the Pfizer and the Moderna vaccines, people tend to have stronger reactions to the second one than they did for the first.” Emily says. “We’re seeing that both in terms of the subjectively reported reactions, people saying they feel fatigued or having chills or being nauseous, stuff like that, but then also in the objective WHOOP data. We’re seeing larger increases in resting heart rate, larger decreases in HRV and recovery, and larger disturbances to the subsequent night’s sleep.” Emily notes that the reactions to the single-dose Johnson & Johnson vaccine look similar to the second Moderna dose. WHOOP has only collected data on the first dose of the AstraZeneca vaccine, which Emily says has shown a similar response to the Johnson & Johnson findings.

8:30 – Pfizer and Moderna Second Dose Data & Effects. Emily says that 71% of those who received the second Moderna dose reported a decrease in recovery, while 65% saw a decrease in heart rate variability and 44% had a 10% or more increase in resting heart rate. For those who received the second Pfizer shot, 60% reported a decreased recovery, 52% saw a dip in HRV, and 27% had an increased resting heart rate. Emily notes that Moderna uses about 4 times the dose than the Pfizer vaccine. “Despite the vaccines working roughly equally well, it seems that the Pfizer one is physiologically the easiest one to receive.”

12:10 – Fatigue: The Most Common Symptom After Second Shot. “Just shy of 80% of people reported fatigue after the second Pfizer and Moderna vaccines. … The majority of people after the first [Pfizer and Moderna] dose will not experience fatigue.”

12:40 – Vaccines’ Impact on Sleep. Emily notes we are seeing a decrease in total sleep time across all vaccines, for the first and second dose, with the second dose having a more significant impact on sleep than the first. “We’re also seeing a decrease in the more restorative stages of sleep, your slow-wave and REM sleep. For the second vaccine, about 50% of people who received Moderna and about 37% of people who received Pfizer had lower quality sleep following that second dose. This totally goes away after one night of slightly disturbed sleep.”

13:41 – Younger People Report More Vaccine Symptoms. “We’re seeing a much stronger reaction in younger people than we are in older groups,” Emily says. “We’re seeing that younger cohorts are experiencing all of the symptoms more frequently across all of the different vaccines and seeing higher incidences of elevated resting heart rate and decreased HRV.” Emily says young people having stronger and more active immune systems than older people is the likely explanation for this.

17:37 – A Quick Return to Baseline. WHOOP data shows that those who do exhibit symptoms or see a change in their data following the vaccine typically only experience these effects for one day.

18:30 – Talk To Your Doctor. “None of the information in this podcast should be interpreted as medical advice. Everybody should talk to their own healthcare providers about what makes the most sense for them.”

20:54 – Booster Shots. Emily details why we’ll likely need more vaccines in the future as the virus continues to mutate. “The Pfizer CEO recently came out and said that they expect we’re going to need a booster in 12 months. That booster is not because the vaccines we’re getting are necessarily wearing off, but because it will actually be a different COVID that we’re getting vaccinated against.”

24:30 – Preparing for Your Vaccine. “It’s probably a good idea to plan to be nice to yourself in the 24 hours after the vaccine,” Emily says. “I wouldn’t schedule a super tough workout after that, maybe plan to be able to get into bed a little bit earlier in order to compensate for what’s likely to be decreased sleep quality, but no real need to do much else. Plan to take it easy.”

25:06 – Sleep Well Before Your Shot. Emily cites research from UCSF that suggests people who are sleep deprived when they are vaccinated are less likely to develop protective antibodies. “We definitely recommend, for all vaccines, first and second dose, to get a good night’s sleep the night before. … It’s a good example of a night where we maybe want to set Sleep Coach to peak.”


COVID Vaccines AMA Recap

Emily also answered WHOOP member questions on the subject via an AMA in our app. Here are some of the highlights not covered in the podcast:

Hi Emily! Curious if you have looked at any data on members who logged testing positive for COVID-19 in close proximity to getting vaccinated, and the impact on vaccine symptoms/response? Thank you! – Megan M

Hi Megan! We haven’t actually looked at that yet – there are so many interesting questions we haven’t had time to answer yet! Because vaccine centers aren’t COVID testing the recipients, we know that a lot of people are unknowingly getting vaccinated with asymptomatic and pre-symptomatic COVID and it doesn’t seem to be dangerous, but it is unclear right now how their symptoms would change.

I am interested in the difference in severity of the side effects as well as HRV, RHR, and recovery between men and women after dose 2? Also, do you plan to examine the data on where women are in their menstrual cycles when receiving the vaccine and how that might affect recovery? It looks like there may be a link between higher levels of estrogen and a more robust immune response. – Lindsay D

Hi Lindsay, I love this question so much, but sadly we haven’t had time to look at the impact of menstrual phase on vaccine responses yet. This would be such an interesting project though, especially with our new menstrual cycle-based sleep coaching feature. That said, we did look at differences between males and females and found that while men and women generally followed the same patterns, women experienced slightly more symptoms.

What is something interesting that you all learned that isn’t too commonly known from the study? – Ray T

Our study is the first to look at objective sleep and recovery data, so we’re the first ones to show that sleep quality is reduced post-vaccination. This has interesting policy implications for policy makers or employers thinking about offering time off for the vaccines. Sleep deprived workers are more likely to make expensive errors or have work place injuries, and sleep deprived drivers are more likely to get into car crashes, so there are a lot of good reasons to give people a day off to recover post-vaccination.

Have you seen people who previously had COVID show negative recovery stats after the 1st or 2nd dose of the vaccine or both? – Chris V

There is some research (not done by us) that seems to suggest that people who have had COVID already will have stronger reactions to the first shot than people who didn’t previously get COVID. We haven’t looked at the relationship between prior COVID and reaction intensity yet but have seen overall that people react more strongly to the second shot than the first shot, but in both cases the reactions are short-lived and people are back to normal in about a day.

Hey Emily! How is the vaccine affecting women nursing? Can you pass antibodies to your baby? Also should you wait until you’re not as sleep deprived? – Gisella C

WHOOP hasn’t studied vaccine reactions in nursing moms, but other research has shown that antibodies do pass to the baby, so nursing might be a really amazing way to protect a baby that is too young to get the COVID vaccine themselves. While vaccines have been shown to be less effective if you are sleep deprived, they still are more protective than not getting the shot at all so if your doctor says you are safe to get vaccinated it is probably not worth delaying too long.

Is there a possibility that with the vaccine, it’s enhanced the body’s immune response to not only COVID-19 but also general viruses? Or is it very specific? – Olivia R

Vaccines are pretty specific. The COVID vaccines will likely protect us against small mutations to the SARS-CoV-2 virus (the virus that causes COVID-19) but unfortunately there is no reason to think that it would protect us against other viruses.


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Will Ahmed

Will Ahmed is the Founder and CEO of WHOOP, which has developed next generation wearable technology for optimizing human performance and health. WHOOP members include professional athletes, Fortune 500 CEOs, fitness enthusiasts, military personnel, frontline workers and a broad range of people looking to improve their performance. WHOOP has raised more than $400 million from top investors and is valued at $3.6 billion, making it the most valuable standalone wearables company in the world. Ahmed has recruited an active advisory board that consists of some of the world’s most notable cardiologists, technologists, marketers, and designers. Ahmed was recently named to the 2021 Sports Business Journal 40 under 40 list as well as 2020 Fortune 40 Under 40 Healthcare list and previously named to Forbes 30 Under 30 and Boston Business Journal’s 40 Under 40. Ahmed founded WHOOP as a student at Harvard, where he captained the Men’s Varsity Squash Team and graduated with an A.B. in government.