Infectious Disease Alert Updates
By Carol A. Kemper, MD, FACP
Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center
Mandating COVID-19 Vaccination for Healthcare Workers — Revisited
SOURCE: Emanuel EJ, Skorton DJ. Mandating COVID-19 vaccination for health care workers. Ann Intern Med 2021;174:1308-1310.
As of this writing, 15 states have issued COVID-19 vaccine requirements for healthcare workers (HCWs), two of which require booster vaccination (California and New Mexico). Only three of these states allow for regular testing as an alternative to vaccination.
In California, as of Dec. 22, 2021, workers eligible for a booster vaccine must receive a booster by Feb. 1, 2022. Those not yet eligible for booster vaccination must be in compliance within 15 days of the deadline. Workers are exempt only if they provide a signed declination based on religious beliefs or a qualified medical exemption, certified by a licensed physician. Testing is not an option. Workers not in compliance with this mandate may not continue to work in high-risk settings after Feb. 1, 2022 (e.g., exposure to the public, jails, hospitals, etc.), regardless of a legitimate exemption, unless the facility seeks a temporary waiver (which is only good through March 21, 2022), effectively forcing valuable staff to recirculate to non-clinical jobs, quit, or be fired.
When I wrote my original commentary to the above article in early December, data on booster vaccination were limited but suggested it prevented up to 88% of symptomatic COVID-19 infections, as well as mitigated disease severity, especially in those at higher risk. Based on such information, HCW vaccine mandates made sense — for the purpose of preventing HCW infection and limiting nosocomial transmission.
Omicron has forced me to reexamine this position. This is a different strain, and a very different surge — and we are seeing plenty of infections in vaccinated and boosted persons. Whole families are infected with COVID-19, including every boosted adult — who anticipated they were going to be largely protected from infection.
- Booster vaccination may provide another layer of protection — but it’s a leaky layer. It only reduces the risk of infection by another degree. How can you mandate a vaccine that is only partly effective/“leaky”? Until better formulated vaccines are available, mandating vaccination as a requirement of employment is not logical. And, any rationale to mandate HCW vaccination for their own protection cannot be a justification for their dismissal; only if the safety of their patients were at issue. People choose to work in all kinds of different fields with varying risks. One also could argue their risk from community infection far outweighs their risk at work, especially now that kids are being allowed back in school. Further, we are allowing essential workers who test positive to continue to work with appropriate personal protective equipment (PPE) if necessary, creating a baseless argument for vaccination/boosting if the goal is to protect patients.
- We need all our workers to do their jobs right now. Mandates may exacerbate existing worker shortages and force facilities to redirect much-needed resources to pushing vaccine agendas.
- The mandate for booster vaccination also is a day late and a dollar short — the surge is happening now. Mandating booster vaccination for Feb. 1 misses the peak need, although it may prepare workers for a future surge. On the other hand, HCWs who got their boosters in October may be less well protected for the next surge. We just don’t know.
- Most importantly, after 22 months, we know that PPE works— PPE is your first and most effective layer of defense, even before a vaccine was available. Few cases of nosocomial transmission have occurred in the past two years — and these mostly were because of inadequate PPE. At our facility, employee-to-employee cases of transmission were more likely to occur at the bar after work.
Mandating less-than-universally-effective vaccination presents a legal and ethical conundrum. Mandates clearly increase the percentage of vaccinated workers and may push those on the fence to get vaccinated. Numerous examples demonstrate how mandates have boosted HCW vaccination to > 97% to 99% in various facilities. However, even in the absence of a mandate, our facility’s annual influenza vaccination in 2019 was 90%. Then, HCWs had a choice to either vaccinate or wear a mask on the job. For the most vulnerable patients, in nursing homes and skilled care, boosting PPE and improving basic infection control practices may be a much better public health measure than mandating vaccination.
I fear public health is going down a rabbit hole on this issue — and, at the least, has backed themselves into a corner. COVID-19 is here to stay — and the looming question becomes, what happens in six months or with the next surge. Will a fourth booster be mandated?
SARS-CoV-2 as a North American Zoonosis
SOURCE: Chandler JC, Bevins SN, Ellis JW, et al. SARS-CoV-2 exposure in wild white-tailed deer (Odocoileus virginianus). Proc Natl Acad Sci USA 2021;118:e2114828118.
The United States Department of Agriculture/Animal and Plant Health Inspection Service (APHIS)/Wildlife Services National Disease Program conducts routine surveillance for a variety of bacterial, viral, and parasitic diseases in the plant and animal worlds. These are the same folks who put Mediterranean fruit fly traps in my mandarin tree — and bleed sentinel chickens every two weeks from March through October, looking for West Nile virus and other mosquito-borne diseases. In 2021, APHIS began examining the prevalence of SARS-CoV-2 antibodies in white-tailed deer throughout several Northeastern states. A total of 624 pre- and post-COVID-19 pandemic serum samples were randomly selected from specimens obtained for disease surveillance in 2011-2021 for other disease entities (e.g., bovine tuberculosis and chronic wasting disease).
Unexpectedly, 152 of 280 samples (40%) from 2021 and three of 100 samples (3%) from 2020 were positive for SARS-CoV-2 antibodies. None of the specimens from 2011-2018 and only one (2%) from 2019 was positive. To evaluate the possibility of cross-reaction with another cervid SARS-like virus, a subset of specimens was tested further using a viral neutralization assay (NA). NA confirmed the results were highly concordant, with the exception of the single positive assay from 2019, suspected to be falsely positive on initial testing.
Interestingly, most of the 2020 specimens were obtained in January through March of that year, and all three positive 2020 specimens were collected in January — early on in the pandemic. If true, then cross-species infection occurred early in the pandemic. Because the specimens collected were described as “opportunistic,” dependent on when a deer was culled or a specimen collected, true seroprevalence over time cannot be derived. Positive specimens were collected, in descending order of frequency, from Michigan (67%), Pennsylvania (31%), New York (19%), and Illinois (7%). However, deer from half of the represented counties were negative, and most positive deer were clustered within a few adjacent counties.
COVID-19 has become a North American zoonosis endemic in the Northeastern white-tailed deer population. Whether it causes symptomatic infection is not clear, but the authors suspect that most infections are subclinical, with viral shedding in nasal secretions and feces. Now that infection has become established in this animal group, it likely will spread easily, as demonstrated by the frequency of positive results in 2021. Animal reservoirs, such as white-tailed deer, provide a source of persistent circulating infection, which can lead to the emergence of different strains, and even the possibility of cross-species gene reassortment. It also means that COVID-19 can never be eradicated as a human pathogen.
VIRSTA vs. PREDICT in Predicting Endocarditis
SOURCE: Peinado-Acevedo JS, Hurtado-Guerra JJ, Hincapie C, et al. Validation of VIRSTA and predicting risk of endocarditis using a clinical tool (PREDICT) scores to determine the priority of echocardiography in patients with Staphylococcus aureus bacteremia. Clin Infect Dis 2021;73:e1151-e1157.
These authors at two different facilities in Medellin, Columbia, compared two predictive scoring methods, VIRSTA and PREDICT, in the evaluation of 922 patients with Staphylococcus aureus bacteremia (SAB). The results were retrospectively compared in their ability to predict infective endocarditis (IE) according to modified Duke criteria and the need for echocardiography. (Recall that modified Duke criteria employ a mixture of two major criteria [organism consistent with an IE-type bacteria and an abnormal echocardiogram], and five minor criteria [fever, predisposing heart condition, injection drug use, vascular or immunologic phenomena consistent with a diagnosis of IE, and serologic evidence of an IE-type organism]).
PREDICT was developed at the Mayo Clinic in Rochester, MN, based on a retrospective cohort of 678 patients. The VIRSTA scoring system was developed in France, based on a prospective evaluation of adults with SAB presenting to eight different university healthcare centers. VIRSTA scoring is based on 10 criteria assessed at 48 hours from the first positive blood culture, including cerebral or pulmonary embolism, meningitis, permanent indwelling cardiac devices, previous history of IE, injection drug use, preexisting valvular disease, vertebral osteomyelitis, community acquisition, severe sepsis or septic shock, elevation of C-reactive protein, and (subsequently) persistence of bacteremia for > 48 hours of antibacterial therapy. A score of 3 or more points is considered high risk for IE, and a score of 2 or fewer points is considered low risk for IE. In contrast, PREDICT takes a different approach, requiring two days of evaluation: at day 2 of SAB, the site of acquisition of the bacteremia and the presence of cardiac devices; and at day 5, the presence of sustained bacteremia > 72 hours. A positive PREDICT score is 4 or more points at day 1 and 2 or more points at day 5; otherwise, it is considered negative/low risk for IE.
In the current Columbian patient group, SAB was defined as adult patients (> 18 years of age) with one or more blood cultures positive for SA (believed not to be a contaminant). The mean age was 57 years; 52.8% were considered nosocomial, 32.1% were healthcare-associated, and 16.7% were considered community-acquired; 26.3% were methicillin-resistant bacteremias. Echocardiography was performed in 600 cases (65%), of which nearly three-fourths were transesophageal. Of the 922 adults with SAB, 62 (6.7%) were diagnosed with IE. Fifty-two cases met the modified Duke criteria for IE (47 cases met two major criteria, and 15 met one major criterion and at least three minor criteria).
When the VIRSTA scoring system was applied, the frequency of IE was 12.8% in those with a positive score (60/468 patients) and 0.44% in those with a negative score (2/454 patients). (These two patients were believed to be falsely negative because they quickly died, and follow-up blood cultures could not be obtained.) In contrast, when the PREDICT scoring system was used in the same group, the frequency of IE was 10.6% in those with a positive score (32/300) and 4.8% in those with a negative score (30/622). The frequency of IE was 10-fold greater in those at low risk using PREDICT vs. VIRTSA, respectively. The median VIRSTA score for those with and without IE, according to Duke criteria, was 7 and 2, respectively. And the median PREDICT score for those with and without IE at day 1 was 1 and 0, and at day 5, was 2 and 1, respectively. The sensitivity and negative predictive value of the VIRSTA scoring system was 96.7% and 99.5%, whereas the sensitivity and negative predictive value of PREDICT at day 5 was 51.6% and 95.1%.
When using the VIRSTA scoring system, echocardiography could be reasonably and safely deferred in those patients with a negative score, who have < 0.5% chance of IE. Thus, nearly half of the echocardiograms performed could have been avoided. In contrast, the frequency of IE was 4.6% in those with a negative PREDICT score — too high to skip echocardiography. The utility of the scoring systems, however, may depend on the populations being studied. The Colombian patient group had fewer cases of IE (6.7%) than either that of VIRSTA (11%) or PREDICT (13%), and the patients were significantly younger, with fewer injection drug users and a lower frequency of cardiac devices and prior IE. Thirty-nine percent of the SABs were related to hemodialysis catheters. All of these factors generally would confer a lower risk of IE in the population studied. It would be interesting to compare the two scoring systems in a higher-risk group.
Mandating COVID-19 Vaccination for Healthcare Workers — Revisited; SARS-CoV-2 as a North American Zoonosis; VIRSTA vs. PREDICT in Predicting Endocarditis
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