require treatment, one is loath to send a patient home when there is a significant probability that they will worsen and require admission later. The patient who is sent home to iso­late, particularly if they live alone, may be understandably fearful. Besides the Covid-19 hotel, two other follow- up options have been piloted. In England, patients discharged to home were given home pulse oximeters and enrolled in a “virtual ward,” where hundreds of patients had remote access to a healthcare practitioner 24h a day who was assigned to monitor them and advise them about self-care and to transfer them to the hospital when necessary [9]. This arrangement may have significantly reduced mortality. In another study, a more common arrangement—providing the patient with pulse oximetry and instructions to come to the Emergency Room if the oxygen saturation dipped below 92% at rest—found that with the 92% cutoff, patients who came to the hospital were there in time to initiate treatment for acute Covid-19 and that 33% of the enrollees who did not come to the hospital would’ve done so if they didn’t have the oximeter [10]. Another arrangement that was tried many places was sending automated text messages to patients—were they improving, staying the same, or getting worse? Those who were getting worse were contacted.

The syndrome has been variously dubbed long covid, post­acute sequelae of Covid-19, or simply post-Covid-19 condi­tion. The World Health Organization definition is generally accepted: “Post Covid-19 condition occurs in individuals with a history of probable or confirmed SARSCoV-2 infection, usually 3 months from the onset of Covid-19 with symptoms that last for at least 2 months and cannot be explained by an alternative diagnosis.” The most common symptoms are per­sistent generalized fatigue [11], dyspnea, and cognitive diffi­culties or “brain fog.” These range in severity from bothersome to severely disabling. Other post-Covid-19 symptoms include headaches, joint pain, tachycardia, chest pain, hair loss, myal­gia, dysgeusia, dysosmia, and insomnia. Of particular note is the high prevalence of persistent—or new—psychiatric symp­toms [12]. Many studies have shown that these post-Covid-19 sequelae occur not only in those patients who’ve had severe Covid-19, but in those with moderate or mild disease as well [13].

clinical improvement is slow, advanced testing and specialty consultation should be initiated even though the 3-month mark may not have been reached.

There are three Covid-19 vaccines approved for use in the United States. See Table1, 2, 3 for the Covid-19 vaccine series schedule for 6 months and older [16]. The Pfizer/BioNTech and Moderna vaccines are both mRNA vaccines. Lipid nanoparticles carrying the mRNA of the coronavirus spike

• Have a low index of suspicion for testing, especially with

high-risk patients.