Tests on monkeys suggest that patients who appear to have been "re-infected" may have been presenting symptoms from the same infection, reports The Daily Telegraph. A team of Chinese scientists that infected monkeys with the novel coronavirus have found those recovering developed effective immunity from the disease.
After initially falling ill, the monkeys produced antibodies and thus could not be re-infected, according to a paper, not peer-reviewed. “Our results indicated that the primary SARS-Cov-2 infection could protect from subsequent exposures,” wrote the team of researchers, led by Qin Chuan from Peking Union Medical College.
The discovery sheds some light on puzzling cases in which patients appeared to relapse, or be re-infected. Some discharged after testing negative for coronavirus later again developed symptoms, even testing positive.
But these latest findings indicate that the infection may not have ever fully cleared in certain cases.
This is positive news for scientists racing to develop a vaccine against the novel coronavirus that emerged late last year in central China, which has infected more than 182,000 people worldwide. Human trials have begun in the US.
Abstract (not peer-reviewed)
An outbreak of the Corona Virus Disease 2019 (COVID-19), caused by the severe acute respiratory syndrome CoV-2 (SARS-CoV-2), began in Wuhan and spread globally. Recently, it has been reported that discharged patients in China and elsewhere were testing positive after recovering. However, it remains unclear whether the convalescing patients have a risk of "relapse" or "reinfection". The longitudinal tracking of re-exposure after the disappeared symptoms of the SARS-CoV-2-infected monkeys was performed in this study. We found that weight loss in some monkeys, viral replication mainly in nose, pharynx, lung and gut, as well as moderate interstitial pneumonia at 7 days post-infection (dpi) were clearly observed in rhesus monkeys after the primary infection. After the symptoms were alleviated and the specific antibody tested positively, the half of infected monkeys were rechallenged with the same dose of SARS-CoV-2 strain. Notably, neither viral loads in nasopharyngeal and anal swabs along timeline nor viral replication in all primary tissue compartments at 5 days post-reinfection (dpr) was found in re-exposed monkeys. Combined with the follow-up virologic, radiological and pathological findings, the monkeys with re-exposure showed no recurrence of COVID-19, similarly to the infected monkey without rechallenge. Taken together, our results indicated that the primary SARS-CoV-2 infection could protect from subsequent exposures, which have the reference of prognosis of the disease and vital implications for vaccine design.
Authors
Linlin Bao, Wei Deng, Hong Gao, Chong Xiao, Jiayi Liu, Jing Xue, Qi Lv, Jiangning Liu, PinYu, Yanfeng Xu, Feifei Qi, Yajin Qu, Fengdi Li, Zhiguang Xiang, Haisheng Yu, Shuran Go, Mingya Liu, Guanpeng Wang, Shunyi Wang, Zhiqi Song, Wenjie Zhao, Yunlin Han, Linna Zhao, Xing Liu, Qiang Wei, Chuan Qin
[link url="https://www.telegraph.co.uk/news/2020/03/17/coronavirus-vaccine-hope-infected-monkeys-can-quickly-develop/?WT.mc_id=e_DM1218948&WT.tsrc=email&etype=Edi_FAM_New_ES&utmsource=email&utm_medium=Edi_FAM_New_ES20200317&utm_campaign=DM1218948"]Full report in The Daily Telegraph[/link]
[link url="https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1"]bioRxiv abstract[/link]