sera for antibody detection can be store for months at -20C and for years at -80.

I would recommend -80

Short time like 1-3 months -20 is O'K, longer -80.

But what about technicians' safety? Do you use any chemical/physical methods for virus inactivation?

1. storage at -80 deg C is the best way.

2. there are special tubes for -80 deg.

3. blood clotting and centrifugation for separation of the sera. I would recommend you to divide your samples into necessary quantities before freezing. So you will avoid multiply cycles of thawing\freezing.

4. it depends of the planning storage period.

Sera can be inactivated at 56 deg C for 30 min. This is the classical method.