Antibodies from Sinovac's 19 shot fade after about 6 months, booster helps - study



(Updates with study details, comment from Philippine health official, background)

BEIJING, July 27 (Reuters) - Antibodies triggered by Sinovac Biotech's SVA.O COVID-19 vaccine declined below a key threshold from around six months after a second dose for most recipients, although a third shot had a strong booster effect, according to a lab study.

Chinese researchers reported the findings from a study of blood samples from healthy adults aged between 18-59 in a paper published on Sunday, which has not been peer reviewed.

Among participants who received two doses, two or four weeks apart, only 16.9% and 35.2% respectively still had neutralising antibodies above what researchers regard as a detectable threshold level six months after the second shot, the paper said.

Those readings were based on data from two cohorts involving more than 50 participants each, while the study gave third doses of the vaccine or placebo to a total of 540 participants.

Researchers said it was unclear how the decrease in antibodies would affect the shot's effectiveness, since scientists have yet to figure out precisely the threshold of antibody levels for a vaccine to be able to prevent the disease.

"In the short-to-medium term, ensuring more people complete the current two-dose schedule of CoronaVac should be the priority," the paper said.

Indonesia and Thailand have already agreed to give a third shot from Moderna and Pfizer respectively for some people who are fully vaccinated with the Sinovac vaccine, amid concerns over its effectiveness against the more transmissible Delta variant of the coronavirus.

Turkey had started offering a third dose from either Sinovac or Pfizer to some people who have got Sinovac shots.

As of end-June, Sinovac has delivered more than 1 billion doses of the vaccine, a major vaccination tool in China, Brazil, Indonesia and Chile.

Philippines' Health Secretary Francisco Duque said on Tuesday there is no recommendation yet from the country's vaccine expert panel on giving a booster shot but experts are discussing the possibility.

The study also said that participants in some cohorts who received a third dose of the Sinovac shot about six months after the second showed around a 3-5 fold increase in antibody levels after a further 28 days, compared with the levels seen four weeks after the second shot.

Researchers cautioned the study did not test the antibodies' effect against more transmissible variants, and that further research was needed to assess antibody duration after a third shot.

The study was conducted by researchers at disease control authorities in Jiangsu province, Sinovac, and other Chinese institutions.
Reporting by Roxanne Liu and Ryan Woo in Beijing, Neil Jerome Morales in Manila. Editing by Mark Potter, Miyoung Kim and Raju Gopalakrishnan

免責聲明: XM Group提供線上交易平台的登入和執行服務,允許個人查看和/或使用網站所提供的內容,但不進行任何更改或擴展其服務和訪問權限,並受以下條款與條例約束:(i)條款與條例;(ii)風險提示;(iii)完全免責聲明。網站內部所提供的所有資訊,僅限於一般資訊用途。請注意,我們所有的線上交易平台內容並不構成,也不被視為進入金融市場交易的邀約或邀請 。金融市場交易會對您的投資帶來重大風險。

所有缐上交易平台所發佈的資料,僅適用於教育/資訊類用途,不包含也不應被視爲適用於金融、投資稅或交易相關諮詢和建議,或是交易價格紀錄,或是任何金融商品或非應邀途徑的金融相關優惠的交易邀約或邀請。

本網站的所有XM和第三方所提供的内容,包括意見、新聞、研究、分析、價格其他資訊和第三方網站鏈接,皆爲‘按原狀’,並作爲一般市場評論所提供,而非投資建議。請理解和接受,所有被歸類為投資研究範圍的相關内容,並非爲了促進投資研究獨立性,而根據法律要求所編寫,而是被視爲符合營銷傳播相關法律與法規所編寫的内容。請確保您已詳讀並完全理解我們的非獨立投資研究提示和風險提示資訊,相關詳情請點擊 這裡查看。

我們運用 cookies 提供您最佳之網頁使用經驗。更改您的cookie 設定跟詳情。

風險提示: 您的資金存在風險。杠杆商品可能不適合所有客戶。 請詳細閱讀我們的風險聲明