In general an antibody test is only going to test IgG levels. Trellis testing can be done but not as a routine. Vit D (D3) is critical for a multitude of issues. I try and take 5000 units a day, unless I was at a beach all day of course. Many years ago during a business discussion with the head clinical pathologist at MD Anderson, supplements and Vit D came up. He made the comment that the ‘normal’ range being used for that assay, vit D, was a joke because essentially we have no idea what normal is. It simply has no substantive data. He said everyone should be taking it, at least 4000 units per day and 5000 would be better. When I asked can you over fo it he said that when someone came in as undernourished they administered 25,000 units via injection so up to 5,000/day was not going to hurt you. Only other comment I would make on this is with that much 4-5,000, I have learned thru some study that vit K is essential for adequate absorption. On the Covid aspect zinc and magnesium are essential (imo) also. And of course there is a drug I take periodically as prophylaxis against Covid but it’s controversial.