If a person developed antibodies after receiving COVID-19, it will be highly unlikely that person would get it again, since the antibodies would kill the virus. This doesn’t mean, a person can’t get influenza by other factors or morphs into other strains.
If the COVID-19 morphs into COVID-20 or worse, then a person that has recovered from COVID-19 would be susceptible to a new infection.
Handbook on biological warfare preparedness-Academic Press (2020)
With the advancements in the field of virology, other viruses such as Ebola virus, Marburg virus, Hanta virus, West Nile virus, Dengue virus, Rift valley fever virus, Nipah virus, and Venezuelan equine encephalitis virus are also appealing biothreat agents for terrorists…(Morse and Meyer, 2017). Various viral biological warfare agents along with their category, mode of dissemination, and vectors involved in their transmission are given in Table 2. P.67
The A to Z of Nuclear, Biological, and Chemical Warfare-2009
VIAN FLU. Avian flu, also called “bird flu,” refers to viral influenza primarily affecting birds. Some human deaths have been attributed to exposure to avian flu virus. These deaths appear to have occurred mainly in cases where individuals have lived or worked in proximity to poultry. Its spread in recent years has led to concern that a highly infectious strain, such as the H5N1 strain, could combine with the common cold virus and result in a human pandemic…The spread of avian flu has highlighted the vulnerability of humans to disease outbreaks, whether from natural causes or deliberate releases. See also SMALLPOX. P.23