It usually takes about 2 to 3 weeks after receiving the Moderna vaccine to develop sufficient immunity against COVID-19. The effectiveness of the vaccine should be around 90% after this period, even with just the first dose. After receiving the second dose, the effectiveness increases to around 95%. The antibodies produced by the vaccine can quickly neutralize the coronavirus to prevent the viral load from increasing. This helps reduce the risk of spreading the virus or developing severe symptoms of COVID-19. While it is still possible to contract COVID-19 after being vaccinated, the illness is likely to be mild. The Moderna vaccine has shown effectiveness against the UK variant of the virus, but its effectiveness against the South African or Brazilian variants may be reduced due to their mutations. Further studies are needed to confirm these findings.