Responsible private behavior in a viral pandemic

I’m trying to figure out how to apply Kant’s categorical imperative to the present situation of viral pandemic. How should I behave such that I would be ok if everyone behaved in the same way as I do? I should also specify that although I hope that I won’t personally get covid-19, I think of myself as in the low risk group, so my own health is not my primary concern. (Of course, If I get very sick, this attitude would change quickly.)

To make it simple, I’d like to allow two types of behavior regarding care in minimizing spread of the virus. With the public (large numbers of people), I am very careful. I don’t go to a large gathering without a mask, shaking many people’s hands, hugging them, and generally sneezing and touching many surfaces over an extended period of time. When I go to the grocery store, I wear a mask and keep my distance. I wash my hands before and after (or wear gloves).

Next, there are a small number of people that I do not practice such a careful approach with. If I were quarantined with my family, that would be the model, but as I am by myself, I should be allowed a certain number of people to see that I have a higher chance of spreading or recieving the virus from. I want to behave in such a way that if everyone followed similar principles, the virus would stay contained and the number of cases would go to zero. Suppose we know the probability of spreading the virus publicly (p_pub) and the number of people I interact with in the public (n_pub). And likewise we know the probability of spreading the virus privately (p_priv) and the nunber of people we interact with privately. From our assumptions, n_pub >> n_priv and p_pub << p_priv. Suppose that for everyone, these numbers were the same (clearly not true, but fits with the Kantian thought experiment). If we know n_pub and p_pub and p_priv what is n_priv so that the global R_0, (the average number of persons infected per infected individual) is less than 1?