Several factors can influence the effectiveness of vaccines, including:
Age - Younger and older individuals may have different immune responses. Health status - Immunocompromised individuals may not respond as well to vaccines. Vaccine type - Live attenuated vaccines, inactivated vaccines, and mRNA vaccines may have varying levels of effectiveness. Virus variants - Changes in the virus can affect vaccine performance. Vaccination coverage - Higher coverage can lead to herd immunity and greater overall effectiveness.
