Vaccines against Middle East respiratory syndrome coronavirus for humans and camels

Abstract

Middle East respiratory syndrome coronavirus (MERS-CoV) is caused by a novel betacoronavirus that was isolated in late 2012 in Saudi Arabia. The viral infections have been reported in more than 1700 humans, ranging from asymptomatic or mild cases to severe pneumonia with a mortality rate of 40%. It is well documented now that dromedary camels contract the infection and shed the virus without notable symptoms, and such animals had been infected by at least the early 1980s. The mechanism of camel to human transmission is still not clear, but several primary cases have been associated with camel contact. There is no approved antiviral drug or vaccine against MERS-CoV despite the active research in this area. Vaccine candidates have been developed using various platforms and regimens and have been tested in several animal models. Here, this article reviews the published studies on MERS-CoV vaccines with more focus on vaccines tested in large animals, including camels. It is foreseeable that the 1-health approach could be the best way of tackling the MERS-CoV endemic in the Arabian Peninsula, by using the mass vaccination of camels in the affected areas to block camel to human transmission. Camel vaccines can be developed in a faster time with fewer regulations and lower costs and could clear this virus from the Arabian Peninsula if accompanied by efficient public health measures.

Keywords: MERS coronavirus vaccine; Middle East Respiratory Syndrome; camel vaccine.

Figure 1

Development of MERS‐CoV vaccines for humans and camels. Three vaccines based on different vectors have been developed and tested (or planned for testing) in camels and in humans. Camel vaccination could block MERS‐CoV transmission and prevent any potential outbreaks in humans, applying the one‐health concept. Vaccinating humans, especially health care workers or individuals with comorbidity, could then further prevent MERS‐CoV infections and outbreaks. Bats are included as a suspected primary host of MERS‐CoV although this is not confirmed. MERS‐CoV can spread from infected camels to (i) naive camels or (ii) humans who may or may not show symptoms but are able to spread the virus to more susceptible individuals, causing an outbreak