1. Researchers conducted a phase 2 A_ B randomized controlled trial to determine the efficacy of NVX-CoV2372 COVID-19 Vaccine against B.1.351 Variant. The trial was conducted in South Africa, where participants were randomly assigned to receive two doses either of the NVX-CoV2372 vaccine or placebo. Participants received at least one injection of vaccine (n=2199) or placebo (n=2188). The primary efficacy end point was confirmed symptomatic Covid-19 that occurred within 7 days after receipt of the second injection. Among 2684 baseline seronegative participants, symptomatic Covid-19 was observed in 15 participants in the vaccine group and in 29 participants in the placebo group. These findings correspond to a vaccine efficacy of 49.4% (95% confidence interval [CI], 6.1 to 72.8).

What conclusion should you make based on the given data?

1. Fail to reject H₀and conclude there is not sufficient evidence to support the claim that the NVX-CoV2373 vaccine is efficient in reducing the risk of B.1.351 Variant.
2. Fail to reject H₀ and conclude there is sufficient evidence to support the claim that the NVX-CoV2373 vaccine is efficient in reducing the risk of B.1.351 Variant.
3. Accept H₀and conclude there is sufficient evidence to support the claim that the NVX-CoV2373 vaccine is efficient in reducing the risk of B.1.351Variant.
4. Reject H₀ and conclude there is sufficient evidence to support the claim that the NVX-CoV2373 vaccine is efficient in reducing the risk of B.1.351 Variant.
5. Reject H₀ and conclude there is sufficient evidence to support the claim that the NVX-CoV2373 vaccine is not efficient in reducing the risk of B.1.351 Variant.

Please explain why it is answer D. Thank you,