The Impact of Gatherings During the Pandemic

On March 6, 2020, I celebrated my friend Doug’s birthday. Little did we know, this would be the last birthday gathering for over a year. Shortly after, the first COVID-19 cases emerged in Connecticut, leading to widespread lockdowns. This gathering now feels like a distant memory, overshadowed by the pandemic's realities. Thankfully, none of us contracted the virus from that event; however, similar small gatherings pose a significant risk for transmission, a fact that is challenging to quantify.

Uncovering the Role of Birthdays

Interestingly, birthdays appear to be a key factor. Since they are relatively random events, they often lead to increased small gatherings, as friends and family come together to celebrate.

The research team, led by Anupam Jena and published in JAMA Internal Medicine, utilized a commercial insurance database that included information from over 6 million individuals. They sought to determine whether there was a noticeable rise in COVID-19 cases in the weeks following a household member's birthday.

To achieve accurate results, the researchers needed to account for various factors, primarily the local prevalence of COVID-19. If the virus is scarce in an area, the risk from birthday gatherings would likely be minimal, whereas high prevalence would suggest a greater risk.

The Findings

Their investigation yielded a compelling link between birthdays and COVID-19 infections. Notably, there was a significant increase in risk, particularly in communities with higher virus prevalence. Households with birthdays experienced a 30% greater risk of infection compared to those without.

Importantly, many people, including myself, chose to forego birthday parties during peak pandemic times. This decision likely underrepresented the true risk of small gatherings.

The researchers undertook a falsification analysis, examining whether the temporal relationship between gatherings and infections could be reversed. If birthday gatherings were indeed responsible for the infections, one wouldn't expect to see increased risk in the weeks leading up to a birthday. Their findings supported the original hypothesis: no reverse correlation was detected.

However, not all aspects of the analysis were conclusive. The researchers specifically looked at milestone birthdays, such as the 40th, 50th, and 60th, expecting these to correlate with larger celebrations. Surprisingly, they found no significant effect.

This lack of correlation may stem from the fact that the most pronounced effects were observed in households with children celebrating birthdays. In high-prevalence areas, these households faced a threefold increase in infection risk compared to those celebrating adult birthdays. This makes sense; it’s easier to skip your own celebration than to deny a child their special day.

Current Perspectives

The situation today differs significantly from the period when this study was conducted. Vaccines have made birthday gatherings considerably safer. Nonetheless, COVID-19 continues to spread, particularly among unvaccinated individuals, highlighting the need to remain vigilant regarding small, intimate gatherings just as much as we do with crowded venues.