There is emerging evidence that COVID-19 affects many systems of the body, with patients reporting a wide range of symptoms. ‘Long-haulers’ are patients who experience ongoing COVID-19 symptoms for several months after infection. These include fatigue, difficulties in thinking, shortness of breath, chest pain, irregular or abnormal heart rhythm, and joint pain. 

The latest research suggests that antibodies can be detected in recovered patients for up to 2 to 3 months after symptoms. There's also emerging evidence for the role of T cells in the immune response. A better understanding of the immune response is vital if there is going to be a successful vaccine.

  • Rapid response

    There are almost 150 coronavirus vaccine candidates under development. Only 19 of these are now being tested in humans. Many types of vaccines are rapidly progressing through clinical trials. Only two vaccine candidates have announced large scale Phase 3 trials, involving several thousands of people. Only one candidate has been approved for restricted human use. Measuring a reduction in COVID-19 levels is an obstacle for Phase 3 clinical trials, as they require a high infection rate among the tested population to prove vaccine efficacy. International agreements with countries where SARS-CoV-2 infection rates are still high are facilitating those trials. Future challenges in vaccine development include a better understanding of COVID-19 immunity and development of vaccination strategies.