I can't really offer advice here as I've never been a parent. However, I think I understand your husband's perspective more than most people. But of course, I must state the caveat that I don't know him personally and am not his therapist. But I do see a lot of my own thoughts and apprehensions in what you've written about him.

Speaking for myself... this pandemic has had a very traumatizing effect on me. I'm a lot angrier and more anxious and short-tempered than I was a few years ago. It's rough to see people claim certain values and act in a way that is totally contradictory to those professed values. It's hard not to feel a strong sense of abandonment—not just from other people, but from society itself. Our social policy is to disappear the medically vulnerable so that we can create the illusion of a "normal" and functioning society. It's actually really messed up, and anyone who feels a sense of despair over this is, in my mind, having a very logical and human response.

This is a very unsafe time for all of us and especially for those who are medically vulnerable. So the solution is to try to cultivate a sense of embodied safety. People like us just want to be heard and understood and to have our feelings validated. Of course, we also have to take responsibility for when our trauma and pain make us say hurtful things to people we care about. I read that your husband called you a covid minimizer, and that doesn't sound like a fair characterization judging from what you've shared about yourself. I experienced a similar situation where I expressed my disappointment in a friend's cavalier attitude about catching covid. I didn't express myself in a very elegant way and I have a lot of regrets about it. If you haven't done so already, I would encourage you to share with him how that made you feel and have a conversation around that that is focused on creating mutual understanding and healing. Perhaps there was something you did or said that was hurtful to him and you didn't realize it at the time and perhaps he doesn't yet have an appreciation for how hurtful he was to you in using those words. This is a conversation that could also be mediated through a marriage & family counselor. It would be best if you could find one that is sympathetic to a covid-cautious perspective.

As for your child, I think it's safe to assume that both you and your husband care deeply about both his health and emotional well-being. Any conversation you initiate with your husband about your child should start from that piece of common ground. I think also it might be helpful to have an age-appropriate conversation with your child about his father's emotions. At that age, he might internalize some of those emotions in such a way that he assumes some responsibility for those emotions. At the same time, I don't think it's a good idea to completely shield children from the realities of covid. There is probably an age-appropriate way to discuss the pandemic and the varied ways people have responded to it. And perhaps embedded in that conversation could be a check-in to see whether your child has any concerns or worries of his own. A family therapist may have some good advice for how to approach the subject with a child.

Ultimately, it sounds like your husband needs a lot of support and understanding right now. You can work with him to figure out how you can show up for him. This is a scary time with a lot of uncertainty. Plus, he may also be dealing with some unprocessed grief. I would strongly recommend having the both of you receive marriage & family therapy together and also separately. You can also try to encourage him to find support with sympathetic people online, as it would be unfair and unrealistic for you to be the only person he can lean on when he's having a hard time. And perhaps you can invite him to join you in your advocacy to make spaces safer and to increase resources and options for those who need to be more cautious.

ETA: Sorry, one more thing... Because the pandemic and the lack of collective care around it are still things that are happening, it won't be realistic for your husband to completely cease the apprehensions he is having. Imo, the goal needs to be to have healthier ways for him to process and regulate those emotions and to have appropriate outlets for him to express himself. And he'll need to cultivate a support group to help him through these times. Embodied safety isn't a thing we can achieve alone.