Acellular vaccines generally do not initiate the strongest immune response. In most cases, one is required to receive a "booster" some time after receiving the first vaccine. Acellular vaccines cannot cause disease and are therefore considered safe.<ref>[http://www.accessexcellence.org/AE/AEC/CC/vaccines_how_why.php Vaccines: Access Excellence]</ref> | Acellular vaccines generally do not initiate the strongest immune response. In most cases, one is required to receive a "booster" some time after receiving the first vaccine. Acellular vaccines cannot cause disease and are therefore considered safe.<ref>[http://www.accessexcellence.org/AE/AEC/CC/vaccines_how_why.php Vaccines: Access Excellence]</ref> |