Most asthma exacerbations are caused by common cold virus infections, predominantly rhinovirus infections. Full protection against repeat infections with the same rhinovirus serotype is given by serum neutralizing antibody, but cross-reactive antibody developed against other serotypes could yield partial protection and result in attenuated cold and airway symptoms. It is proposed that vaccine-mediated induction of cross-reactive antibody might not prevent rhinovirus infections but might reduce severe asthma symptoms and exacerbations.