Acute infections are rapid and produce a large amount of new virus soon after infection. Acute infections are also cleared quickly by the immune system so production of new virus only occurs for a short period of time. Latent infections don’t produce a large amount of new virus in the short-term as they integrate into the host DNA, but they can be reactivated at a later date and produce a substantial amount of new virus upon reactivation. The virus remains in the host DNA and can be reactivated many times, so in the end a latent infection could produce more new virus than an acute one.
In this chapter we talked about how important herd immunity can be with regard to infection. Recall from earlier chapters herd immunity is based on how many people in a population have been exposed to a particular infection. The more people that have been exposed either through naturally coming in contact with the virus or through vaccination, the more people that are immune to infection. The higher the number of immune individuals, the lower the number of potential targets for infection and the more limited the transmission of the infection.
The best vaccine will be effective, safe and preferably inexpensive. There are several types of vaccine; those that include killed virus, those that are made with inactive virus and those made from pieces of virus called subunit vaccines. The inactive form of vaccine seems to provide more protection but there can be concerns about safety since the virus is not killed. That safety
Concerns are not seen in vaccines made up of killed virus or the subunit form of vaccine but these may not give the highest level of protection