The release of Johnson & Johnson’s Covid-19 vaccine and its partnership with Merck means that President Joe Biden expects the US to have enough Covid-19 vaccines delivered to cover every adult by the end of May. If Johnson & Johnson and fellow vaccine makers Moderna and Pfizer meet their vaccine pledges, the bigger question we may soon be facing isn’t whether we have enough doses of Covid-19 vaccines, but whether people will actually take them. Recent polling suggests a continued drop in the vaccine hesitant population as more and more people get vaccinated in the US. The past two weeks alone, there were two polls that show just how much vaccine hesitancy has declined. The Kaiser Family Foundation poll found that 55% of adults say they now want a Covid-19 vaccine as soon as possible or have already received their first dose. That’s up from 47% in January and 34% in December. While the percentage of hardline “get it only if required” or “definitely not” has remained fairly consistent at or just north of 20%, the hesitant population of “wait and see how it’s working” has dropped by nearly half during the last two months from 39% to 22%. Axios/Ipsos polling shows a similar trendline. A mere 13% of adults said in September they would get a Covid-19 vaccine as soon as it was made available to them. That jumped to 27% in early December to 43% in early January. Now, 57% say they have already received the vaccine or will get it as soon as possible. Like in the Kaiser polling, the hardline vaccine resistant population (i.e. people who say they will not get the vaccine or will only get it if forced) is basically the same size now (18%) as it was in September (23%) and early January (19%). More people who say they will wait a period of time (a few weeks to a year or more) to get the vaccine has decreased rapidly: 64% in September, 51% in early December, 38% in early January and 28% now. Unfortunately, it will be hard to convince the vaccine resistant population. The fact that this proportion of the population has remained fairly constant (at around 20%) is an indication that even a load of evidence that the vaccines are safe and effective and is our most likely path back to a normally functioning society won’t shift them. The good news is that the declining percentage of those in the middle (i.e. the vaccine hesitant) is what we would expect as more and more people are safely vaccinated. Even before the FDA approved the vaccines, I pointed out that a big driver of vaccine hesitancy was that people wanted to know the vaccine was safe and effective. It’s still the case that willingness to get the vaccine is correlated with vaccine knowledge and knowing people who have gotten the vaccine. To reach herd immunity through vaccination, scientists believe somewhere between 70% and 90% of the population will need a vaccination. We will only reach that percentage if more people in the vaccine hesitant population become convinced to take the vaccine as soon as it is made available to them. That’s why the next few months will be key. Given Johnson & Johnson’s one shot regimen and Pfizer and Moderna’s two-shot regimen, we are still a few months away from there being enough vaccines for everybody. If the current vaccine delivery timeframes hold and the lionshare of vaccine hesitant people convert into those who will get the vaccine immediately, we could have enough vaccines for every adult who wants one even earlier than the end of May – and we’ll have a much better chance of containing the coronavirus.