Editor's note: As the world grapples with the Delta variant, will existing vaccines protect you? Eric Ding, senior fellow at the Federation of American Scientists, told CGTN anchor Wang Guan that the Delta variant will really be the next challenge and, even if you're vaccinated, it's not a bulletproof vest against being sick or transmitting the virus. Only with all measures including vaccines, masks, testing and border quarantine, together, can we contain the Delta variant. 

Wang Guan: The world is still grappling with the Delta variant, what is next？

Eric Ding: I think the Delta variant is a pandemic 2.0 variant. It is faster, it is the fastest strain we've ever seen, twice as fast as the old strain. It is much more severe. Data from both UK and Singapore says it is 4 to 5 times greater risk of hospitalization than the original strain. And it has reinfection potential, anywhere from 25% of people previously infected are not fully protected.

Eric Ding: And the vaccine, one dose is not enough anymore. You need two doses. Even with two doses, we know that the best two-dose vaccine like Pfizer have, instead of 95% of efficacy, have in the upper 60% and 70% according to Israel and UK data. So, I think Delta variant will really be the next challenge: it is faster, stronger in every way. And what used to work against the virus will not work as well anymore. And even if you're vaccinated, it is not a bulletproof vest against being sick or more importantly transmitting it. Because I think being vaccinated is good - it makes the disease milder. But also many people are asymptomatic and could actually transmit, allow the virus to transmit more if we don't have other measures. So I am pro-vaccine, but we need vaccine, plus mask, plus testing, plus border quarantine and all these measures together. Only together can we contain the Delta variant. We cannot just rely on vaccines alone. We cannot rely on testing alone.

Wang Guan: Thank you for this warning. Eric Ding, senior fellow from the Federation of American Scientists, thank you for joining us.

Eric Ding: Thank you.

Script: Wang Guan, Yang Zhipu, Deng Yutong

Editors: Yang Zhipu, Hao Xinxin, Deng Yutong

Designer: Qi Haiming

Producer: Zhao Yunjie, Wang Ying

Supervisor: Mei Yan

(If you want to contribute and have specific expertise, please contact us at opinions@cgtn.com.)