So currently the only widely available covid vaccines are the mRNA ones, as Astra Zeneca and Johnson and Johnson aren't getting used in non-elderly populations

So currently the only widely available covid vaccines are the mRNA ones, as Astra Zeneca and Johnson and Johnson aren't getting used in non-elderly populations due to safety issues. Both Pfizer and Moderna are two dose vaccines, and many people have had such severe reactions to the first dose that they are being told by their doctors to not take a second dose. That's not considered vaccinated by many definitions; unclear how the Linux Foundation would treat people in that situation. Similarly, there are people who have received the first dose of Astra Zeneca prior to it getting discontinued in their country. Depending on where they are they aren't necessarily eligible to receive a second dose of any covid vaccine, as mixing-and-matching isn't considered sufficiently well studied by many doctors to recommend it. Again, they're not considered vaccinated by many definitions. There's also people from countries like India and Canada who have gotten non-WHO/non-CDC approved covid vaccines. Does that count as vaccination? Again, many doctors will refuse to give them another WHO/CDC approved covid vaccine due to the unknown risks of getting multiple vaccines. This problem has already come up in Canada with foreign students, and even in the US with Astra Zeneca: https://www.thestar.com/news/canada/2021/06/19/broadway-changes-its-tune-on-astrazeneca-canadians-who-got-that-vaccine-can-now-attend-springsteen-show.html https://www.thestar.com/news/canada/2021/06/19/broadway-chan... Finally, the WHO says that children under the age of 18 should not be vaccinated for covid at this time, a position many other countries are following. Again, they have no way to get vaccinated. The Linux Foundation may of course already ban minors for other reasons. But again, this would prevent most teens from attending their events for the foreseeable future.