Biology Essay Assignment Due Word Count 1180 Challenges of developing vaccines A comparison between HIV and SARS CoV2 Considering both specific viral life cycles and types of associated pandemics, dis. Biology:Essay AssignmentDue:Word Count: 1180Challenges of developing vaccines: A comparison between HIV and SARSCoV2 Considering both specific viral life cycles and types of associated pandemics, discuss the key reasons that can help explain why several vaccines against SarsCoV2 have been developed in record time, but there is still no vaccine against HIV forty years after its emergence. We have experienced two pandemics in the last halfcentury: the human immunodeficiency virus (HIV) and the critical acute respiratory syndrome coronavirus 2 (SARSCoV2) infections. Both are caused by biological viruses that have reached us from animals (Wu A et al.2019). Although these two viruses are distinct in the transmission mode and the symptoms they generate, they have significant similarities., we have experienced two pandemics, the human immunodeficiency virus (HIV) and the severe acute respiratory syndrome coronavirus 2 (SARSCoV2) infections. Both are caused by biological viruses that have reached us from animals. This paper will compare HIV and SARSCoV2 while scrutinizing the key reasons that explain why several vaccines against SarsCoV2 have been developed in record time. However, there is still no vaccine against HIV forty years after its emergence.HIV infection was found in the 80s (1981), when the first cases were known in young adults in California. It is supposed that HIV spread to humans through direct contact with the infected blood of chimpanzees by hunting them for their meat (Lu R et al.2020). Although there is no remedy for HIV infection, effective antiretroviral therapy (ARTs) can regulate the virus and help prevent transmission to other people. In the case of SARSCoV2, the first cases were stated in December 2019 in Wuhan, in the Chinese province of Hubei (Montoya WR et al., 2012). There were 41 cases of people with pneumonitis, 66% of whom had a workday in a seafood market where all kinds of fish and meat were sold, so it is thought that the source might be there. On March 11th, 2020, when globally confirmed cases exceeded 118,000, and the number of deaths was 4,291, the WHO characterized the SARSCoV2 infection as a pandemic named CoronaVirus (COVID19). From that day on, most countries have suffered the infection, and it is not yet controlled.About Specific viral Life circles, on the first hand, Coronavirus( SARSCoV2) is transmitted through the air, mainly due to tiny drops of saliva from infected people by coughing or sneezing that can reach two meters (Zhu N et al.2019). The symptoms generated by SARSCoV2 begin to emerge between 2 and 14 days after contact with the virus. The most typical symptoms include cough, fever, and dyspnea. Diarrhea and abdominal pain are also frequent. Although most cases have mild symptoms, the infection can cause pneumonia, kidney failure, severe difficulty breathing, and even death in the most rigid cases.On the other hand, The symptoms generated by HIV infection begin to appear between 2 and 6 weeks after contact with the virus. They can be divided into an early infection (within the first two months after infection) or chronic (Tortorici et al., 2019). Infected people present fever, muscle pain, headache, rashes, sore throat and mouth sores, and swollen lymph nodes during the infections early or acute phase. These symptoms can be so light that they are almost not noticed. In the phase of chronic infection, the virus continues expanding and destroying immune cells, inducing immunosuppression. Typically, if it is not treated, HIV turns into AIDS in an average of 10 years. When AIDS befalls, the immune system is already seriously damaged, opportunistic infections, neurodegenerative diseases and cancers transpire in infected individuals. COVID19 seems not to be very distinct from SARS regarding its clinical features. Though, it has a fatality percentage of 2.3%, lower than that of SARS (9.5%) and much lower than that of MERS (34.4%)(N Petrosillo et al.2020). The possibility cannot be dismissed that the less severe clinical picture of COVID19 can grow in the community more quickly than MERS and SARS. The actual primary reproductive number (R0) of COVID19 (2.02.5) is still debatable. It is probably slightly higher than the R0 of SARS (1.71.9) and higher than that of MERS (