She must have developed immunity. Use mask and head shield. to prevent spread of infection  from mother to baby.

Hello. Viral infection can spread from one person to another anytime, especially from adult to kids as they are smaller in age and more prone to catch infection. There are different strains and types of viruses, so infection with a virus cannot give 100% protection from reinfection either with same virus or different virus. So, chance of reinfection cannot be ruled out.