看看美国各地的药柜.S. and you’ll find stacks of leftover COVID-19 tests.

When symptoms arise, so do questions: When should I test? 它到底有多准确? 如果检测呈阳性，我该怎么办?

在6月14日发表的一篇论文中 发表在《博彩app推荐》杂志上, CU Boulder researchers unveil a new 数学ematical model to quickly answer such questions, not only for COVID but also for emerging rapid tests for respiratory syncytial virus (RSV), 流感和其他传染病.

One key takeaway: Advice can differ widely depending on the bug.

“对于COVID, 博彩平台推荐发现，如果你只有一个测试, it’s best to wait two days after symptoms arise to use it, because the virus is unlikely to be detectable until then,第一作者凯西·米德尔顿说, a doctoral student in the department of Computer 科学 and the IQ Bio program. “For flu and RSV, you’re best off to take that rapid test when you first feel symptoms.”

DIY测试的新时代

Middleton and senior author Daniel Larremore, a professor of computer science at the BioFrontiers Institute, developed the model to address several challenges that have emerged with the post-pandemic proliferation of rapid tests.

近年来，许多公司纷纷推出 “一体化” tests that check for SARS-CoV-2 (the virus that causes COVID-19), 甲型和乙型流感, 同时感染RSV病毒, and some doctor’s offices and pharmacies offer a combo, 在你等候选项.

与此同时, 居家检测已成为常态, with people routinely self-collecting nasal swabs to protect friends and family.

“If you’re trying to make a decision about whether to go to book club or go to Bingo night with the grandparents, 测试是一个非常好的主意,拉雷莫尔说, 谁的实验室结合了计算机科学, 数学, epidemiology and biology to address public health challenges. “但COVID已经改变了, each variant behaves differently and that means the way that they interact with tests may be different.”

When he and Middleton plugged information about Omicron variants, patient behavior and other factors into their new computational model, it revealed that if a person with COVID tests immediately with a rapid test when symptoms emerge, they receive a false negative as much as 92% of the time. Waiting two days after symptoms brings that rate down to 70%. For those who can afford to take a second test on day 3, 假阴性率下降, with the tests catching about a third of infections.

这是因为, with most people already previously exposed, their immune systems are primed to react upon seeing COVID again, and that immune response itself causes symptoms. 除了, new variants in folks with some immunity grow slightly more slowly than the original strain.

“博彩平台推荐的症状出现得更快了, but it takes longer to reach enough virus in your body for it to be detectable,米德尔顿说。.

有呼吸道合胞病毒和流感, 另一方面, the virus multiplies so quickly that once symptoms set in, there’s already plenty to make a test show up positive.

“这是一个难题，”拉雷莫尔说. “If you go in right away and test for all three, you can learn a lot from the flu and RSV tests, 但对于COVID，你可能太早了. 如果你再等几天, the timing might be right to catch COVID but you are too late for flu and RSV.”

While a 66% false negative rate may seem high for a COVID test, Larremore notes that the tests are designed to identify folks who have a high viral load and are, 因此, 最有可能传染他人.

“Diagnosing only one third of infections can still cut transmission substantially if we've diagnosed the most infeciouts third,他说.

反思孤立政策

Assuming that enough at-home tests are available, their study also suggests that a “test to exit” strategy—in which people test again before determining whether to return to work and socialize—can prevent more COVID infections with less inconvenience than the five-day isolation policy that was standard Centers for Disease Control advice until March.

“The five-day isolation policy made people isolate for too long in most cases,米德尔顿说。. “Test-to-exit does a good job releasing people early who aren’t going to transmit but holding those who still have high amounts of virus.”

Larremore’s previous research was instrumental in informing how COVID-19 vaccines were distributed early in the pandemic and for helping to convince policymakers to prioritize rapid testing.

He and Middleton hope that their new model can help companies develop better tests, 帮助临床医生提供更好的建议和, 如果出现另一次大流行, 使政策制定者能够提供迅速, 数据驱动的测试指导.

如果操作正确的话, the next generation of rapid tests have the potential to be really impactful,拉雷莫尔说.