What was a significant challenge in developing a vaccine for SARS?

The significant challenge in developing a vaccine for SARS was the short duration of immunity. This issue posed a critical barrier because a vaccine needs to elicit a long-lasting immune response to provide protection against future infections. In the case of SARS, initial studies suggested that any immunity generated may not be durable enough, raising concerns about the vaccine's long-term efficacy.

This challenge highlighted the complexity of the immune response to the SARS coronavirus and emphasized the importance of not only generating an immune response but also ensuring that the immunity lasts long enough to protect individuals effectively. It's vital for vaccine developers to understand how long the protection lasts and whether booster doses might be needed, further complicating the vaccine development process.

Other factors that could come into play, such as public interest, funding, or availability of viral samples, were not primary obstacles in the same way that the concern over short-lived immunity presented, which directly impacts the vaccine’s ultimate effectiveness and public health utility.