还没有注射过新冠肺炎疫苗的美国成年人应该考虑一种来自Novavax的新选择——一种更传统的疫苗，健康官员们周二表示。
监管机构上周批准了美国首个所谓的新冠肺炎蛋白疫苗，但最后的障碍是疾病控制和预防中心的建议。
“如果你一直在等待一种基于不同于以往技术的新冠肺炎疫苗，现在是时候加入数百万已经接种疫苗的美国人的行列了，”疾病预防控制中心主任罗谢尔·瓦伦斯基博士在一份声明中说，并赞同一个有影响力的顾问小组早些时候的决定。
到目前为止，大多数美国人至少已经接种了初级新冠肺炎疫苗，但疾病预防控制中心官员表示，2600万至3700万成年人没有接种过一次疫苗，这是诺瓦瓦克斯目前的目标人群。
“我们真的需要关注这些人群，”疾病预防控制中心顾问奥利弗·布鲁克斯博士说，他是国家医学协会的前任主席。希望疫苗“能让他们从不接种疫苗转变为接种疫苗。”
虽然还不清楚有多少人会被更传统的选择所说服，但“我对这种疫苗非常乐观，”俄亥俄州立大学的研究员顾问巴勃罗·桑切斯博士表示同意。
诺瓦瓦克斯的差异
所有的疫苗在美国用来训练身体对抗冠状病毒通过识别其外壳，刺突蛋白-和前三种选择基本上将人的细胞变成了临时疫苗工厂。辉瑞和Moderna疫苗为身体提供遗传指令，以复制刺突蛋白。较少使用的约翰逊& Johnson option使用感冒病毒来传递这些指令。
相比之下，Novavax疫苗注射的刺突蛋白副本在实验室中生长，并包装成纳米颗粒，对免疫系统来说类似于病毒。另一个不同之处是:添加了一种叫做佐剂的成分，这种成分是由一种南美树的树皮制成的，可以帮助提高免疫反应。
蛋白质疫苗已经被用于预防其他疾病多年，包括乙型肝炎和带状疱疹。
它工作得多好
在美国、墨西哥和英国进行的大型研究发现，两剂Novavax疫苗是安全的，在预防有症状的新冠肺炎方面约有90%的有效性。去年夏天，当delta变异体出现时，Novavax报告说，加强剂量可以提高抗病毒抗体，可以对付这种变异体。
典型的疫苗反应是轻微的，包括手臂疼痛和疲劳，但监管机构确实警告了一种罕见风险的可能性，即心脏炎症，辉瑞和Moderna疫苗也出现了这种情况，主要发生在十几岁的男孩或年轻男子身上。
但在早期，制造问题推迟了Novavax疫苗——这意味着在omicron变种出现之前很久就对疫苗进行了研究，所以不清楚它们对免疫逃避突变体的抵抗能力如何。
尽管如此，诺瓦瓦克斯指出，实验室测试表明，前两次注射确实刺激了抗病毒抗体的产生，这些抗体对奥米克隆具有交叉保护作用，包括目前全国最大的威胁BA.5亚型。加强剂量进一步提高了交叉保护抗体。
如何使用诺瓦瓦克斯镜头
疾病预防控制中心的顾问们一致支持这两场初选。但一些人指出，监管机构在最后一剂诺华伐克斯接受者需要加强剂时，即最后一剂后五个月左右，批准加强剂是很重要的。
此外，两种剂量通常相隔三周给药。但疾病预防控制中心官员表示，与其他新冠肺炎疫苗一样，第二剂疫苗可能需要等待长达八周的时间，但高危人群除外，他们需要尽快得到保护。
接下来会发生什么
瓦伦斯基签署了成年人接种首两剂诺瓦克疫苗的建议。在第一次购买中，美国政府购买了320万剂疫苗，预计疫苗接种将在未来几周内开始。
Novavax疫苗也在欧洲、加拿大、澳大利亚、韩国和其他国家使用。许多国家允许加强剂量，欧洲监管机构最近批准12岁儿童注射。
这家总部位于马里兰州的公司同样预计，美国将很快批准加强剂量和青少年疫苗接种。
和其他疫苗制造商一样，Novavax正在测试更新的疫苗，以更好地匹配最新的omicron亚型——预计今年秋天和冬天将有另一轮加强。
CDC endorses more traditional Novavax COVID shot for adults
U.S. adults who haven’t gotten any COVID-19 shots yet should consider a new option from Novavax -- a more traditional kind of vaccine,healthofficials said Tuesday.
Regulators authorized the nation’s first so-called protein vaccine against COVID-19 last week, but the final hurdle was a recommendation from the Centers for Disease Control and Prevention.
“If you have been waiting for a COVID-19 vaccine built on a different technology than those previously available, now is the time to join the millions of Americans who have been vaccinated,” Dr. Rochelle Walensky, CDC's director, said in a statement, endorsing an earlier decision from an influential advisory panel.
Most Americans have gotten at least their primary COVID-19 vaccinations by now, but CDC officials said between 26 million and 37 million adults haven’t had a single dose -- the population that Novavax, for now, will be targeting.
“We really need to focus on that population,” said CDC adviser Dr. Oliver Brooks, past president of the National Medical Association. Hopefully, the vaccine "will change them over from being unvaccinated to vaccinated.”
While it’s unclear how many will be persuaded by a more conventional option, “I'm really positive about this vaccine,” agreed fellow adviser Dr. Pablo Sanchez of Ohio State University.
THE NOVAVAX DIFFERENCE
All of thevaccinesused in the U.S. train the body to fight thecoronavirusby recognizing its outer coating, the spike protein -- and the first three options essentially turn people’s cells into a temporary vaccine factory. The Pfizer and Moderna vaccines deliver genetic instructions for the body to make copies of the spike protein. The lesser-used Johnson& Johnson option uses a cold virus to deliver those instructions.
In contrast, the Novavax vaccine injects copies of the spike protein that are grown in a lab and packaged into nanoparticles that to the immune system resemble a virus. Another difference: An ingredient called an adjuvant, that’s made from the bark of a South American tree, is added to help rev up that immune response.
Protein vaccines have been used for years to prevent other diseases including hepatitis B and shingles.
HOW WELL IT WORKS
Large studies in the U.S., Mexico and Britain found two doses of the Novavax vaccine were safe and about 90% effective at preventing symptomatic COVID-19. When the delta variant emerged last summer, Novavax reported a booster dose revved up virus-fighting antibodies that could tackle that mutant.
Typical vaccine reactions were mild, including arm pain and fatigue, but regulators did warn about the possibility of a rare risk, heart inflammation, that also has been seen with the Pfizer and Moderna vaccines, mostly in teen boys or young men.
But early on, manufacturing problems delayed the Novavax vaccine — meaning the shots were studied long before the omicron variant hit, so it's not clear how well they hold up against the immune-evading mutant.
Still, Novavax points to lab testing that shows the first two shots do spur production of virus-fighting antibodies that are cross-protective against omicron, including the BA.5 subtype that’s currently the nation’s top threat. A booster dose further revved up cross-protective antibodies.
HOW TO USE NOVAVAX SHOTS
The CDC’s advisers unanimously endorsed the two-shot primary series. But several noted that it was important for regulators to clear a booster by the time, five or so months after their last dose, that Novavax recipients will need one.
Also, the two doses typically are given three weeks apart. But CDC officials said that like with other COVID-19 vaccines, it's possible to wait up to eight weeks for the second dose — except for people at the highest risk, who need protection quickly.
WHAT HAPPENS NEXT
Walensky signed off on recommendations for adults to get the first two Novavax doses. In its first purchase, the U.S. government bought 3.2 million doses and vaccinations are expected to begin in the next few weeks.
The Novavax vaccine also is used in Europe, Canada, Australia, South Korea and other countries. Many allow booster doses, and European regulators recently cleared the shots to given as young as age 12.
The Maryland-based company likewise expects U.S. authorization of a booster dose and teen vaccinations to follow fairly soon.
And like other vaccine makers, Novavax is testing shots updated to better match the newest omicron subtypes -- in anticipation of another round of boosters this fall and winter.
