By: David Ostrowsky It’s a daunting Venn diagram – the interplay of three potentially fatal diseases: Respiratory Syncytial Virus (“RSV”), COVID-19, and influenza. And with summer slipping into fall, this triple-headed monster is (once again) threatening to rear its ugly head. But, thanks to modern medicine, could this cold-weather season have a less devastating toll on humanity than what transpired a year ago? As has been well publicized this past week, there is in fact reason for optimism as updated COVID-19 vaccines from Pfizer and Moderna targeting the devilish Omicron variant XBB.1.5 will soon hit the market. It’s a promising development that, combined with the emergence of the first-ever shots to shield older adults and infants from RSV, behold potential to blunt the impact of another “tripledemic” of respiratory viruses. But naturally, the new breakthroughs have sparked a flurry of questions, some of which lack definitive answers. Is the RSV vaccine safe? Are the vaccines for RSV, COVID-19, and influenza recommended for everyone? When should one receive the vaccines? Is it effective or even safe to have multiple shots during the same visit or is separation more prudent? While federal health officials are banking on the widespread adoption of such immunizations to avoid a repeat of last winter, there is, in many cases, simply a dearth of knowledge regarding this multifaceted topic. What we do know: RSV looms as a severe respiratory threat to older adults (particularly those over 75 who have preexisting conditions such as cardiovascular disease, chronic lung disease, or diabetes) as well as newborns and infants. Last month, the Centers for Disease Control and Prevention (“CDC”) did advocate for a new shot against RSV – Beyfortus, a monoclonal antibody – for both infants less than eight months old and infants eight months to nineteen months at risk for serious illness. Also in August, the Federal Drug Administration (“FDA”) did greenlight the use of Pfizer’s vaccine, Abrysvo, for pregnant women as a means of protecting infants from contracting RSV. Perhaps the most pressing matter is that of the timing for inoculation. While COVID-19, RSV, and influenza are all expected to significantly resurge this fall, a more precise timetable is very challenging to gauge. This is due in large part to the seasonal patterns of influenza and RSV being out of whack amidst the yearslong pandemic. For example, last winter, the flu crested in December instead of in February, when it traditionally does; meanwhile, RSV peaked several weeks earlier than usual last year and it circulated longer than it would in the pre-pandemic era. While scientists predict that the flu and RSV will eventually return to their pre-pandemic patterns, it may be a couple years before that materializes. Along the same lines, many are wondering just how safe it will be to receive multiple vaccines concurrently. Unfortunately, there’s much ambiguity surrounding this question. Though many received the influenza and Covid vaccines together last fall without reporting issues, ( “The available data pertaining to the administration of influenza and COVID-19 vaccines at the same time do not indicate safety concerns,” the Department of Health and Human Services said in a statement to The New York Times), the RSV vaccine is still a great unknown. While some research suggests that the RSV and flu vaccines produce lower levels of antibodies when administered together than when delivered separately, there simply isn’t sufficient information about how it might interact with the other two vaccines. The CDC is expected to make recommendations later this fall – a matter of great importance to many Americans who are not inclined or even able to make multiple stops to a clinic or pharmacy to space the shots apart. Hopefully, in the coming weeks, there will be more clarity for such issues, which in turn would ease the burden on healthcare clinics, urgent care centers, and hospitals bracing for (or in some cases already dealing with) an onslaught of patients suffering from respiratory illnesses.