Covid Reference

Page 366

366

|

CovidReference.com

Reactivations, reinfections Seasonal coronavirus protective immunity is not long-lasting (Edridge 2020). There are several reports of patients infected with SARS-CoV-2 who became positive again after negative PCR tests (Lan 2020, Xiao 2020, Yuan 2020). These reports have gained much attention, because this could indicate reactivations as well as reinfections. After closer inspection of these reports, however, there is no good evidence for reactivations or reinfections, and other reasons are much more likely. Methodological problems of PCR always have to be considered; the results can considerably fluctuate (Li 2020). Insufficient material collection or storage are just two examples of many problems with PCR. Even if everything is done correctly, it can be expected that a PCR could fluctuate between positive and negative at times when the values are low and the viral load drops at the end of an infection (Wölfel 2020). The largest study to date found a total of 25 (14,5%) of 172 discharged COVID-19 patients who had a positive test at home after two negative PCR results at hospital (Yuan 2020). On average, the time between the last negative and the first positive test was 7,3 (standard deviation 3,9) days. There were no differences to patients who remained negative. This and the short period of time suggest that in these patients, no reactivations are to be expected. However, in recent months several case reports of true (virologically proven: phylogenetically distinct strains) re-infections have been reported (To 2020, Gupta 2020, Van Elslande 2020). In most cases, the second episode was milder than the first. However, there is at least one case where the second infection was more severe, potentially due to immune enhancement, acquisition of a more pathogenic strain, or perhaps a greater in-oculum of infection as the second exposure was from within household contacts (Larson 2020). Up to now, however, these are anecdotal case reports. Animal studies suggest that re-infection is unlikely (Chandrashekar 2020). Following initial viral clearance and on day 35 following initial viral infection, 9 rhesus macaques were re-challenged with the same doses of virus that were utilized for the primary infection. Very limited viral RNA was observed in BAL on day 1, with no viral RNA detected at subsequent timepoints. These data show that SARS-CoV-2 infection induced protective immunity against reexposure in nonhuman primates. There is growing evidence for a long-lived and robust T cell immunity that is generated following natural SARS-CoV-2 infection (Neidleman 2020). Reactivations as well as rapid new infections would be very unusual, especially for coronaviruses. If a lot of testing is done, you will find a number of such patients who become positive again after repeated negative PCR and clinical

Kamps – Hoffmann


Turn static files into dynamic content formats.

Create a flipbook

Articles inside

References

1hr
pages 497-554

Management

10min
pages 491-496

Diagnosis and classification

11min
pages 484-490

Transplantation

4min
pages 472-473

Transmission

4min
pages 482-483

Pathophysiology and immunopathology

4min
pages 480-481

Natural course and risk factors for complications

2min
page 479

Epidemiology of COVID-19 in children

2min
page 478

Cancer

8min
pages 468-471

Immunosuppression (other than HIV

3min
pages 466-467

HIV infection

6min
pages 463-465

COPD and smoking

4min
pages 461-462

Hypertension and cardiovascular co-morbidities

14min
pages 452-458

Diabetes mellitus

4min
pages 459-460

References

6min
pages 447-451

Special situations in severe COVID-19

3min
pages 445-446

References

25min
pages 429-440

Spotlight: The situation in a German COVID-19 hospital

4min
pages 443-444

Outlook and Recommendations

1min
page 428

4. Immunomodulators

19min
pages 415-424

Other treatments for COVID-19 (with unknown or unproven mechanisms of action

5min
pages 425-427

3. Monoclonal Antibodies and Convalescent Plasma

13min
pages 408-414

2. Various antiviral agents

5min
pages 405-407

1. Inhibitors of the viral RNA synthesis

11min
pages 399-404

Monitoring, treatment options

3min
pages 391-392

Studies with objectifiable tests

3min
pages 389-390

Reactivations, reinfections

2min
page 366

Outcome

27min
pages 352-365

Clinical classification

1min
page 351

Laboratory findings

6min
pages 347-350

References

21min
pages 324-332

Asymptomatic cases

4min
pages 334-335

Radiology

6min
pages 321-323

Incubation period

1min
page 333

Symptoms

21min
pages 336-346

Diagnosis

36min
pages 303-320

References

55min
pages 277-302

Outlook

5min
pages 272-276

Single Vaccines

24min
pages 247-261

Coming vaccines

8min
pages 267-271

Special Topics

9min
pages 241-246

Approved Vaccines

2min
pages 223-224

References

21min
pages 211-222

Outlook

1min
page 210

Transmission

1min
page 187

Epidemiology

11min
pages 175-186

Summary – 13 February

1min
page 173

Genomic Structure and Variation

4min
pages 164-166

References

8min
pages 167-172

Origin and Evolution

4min
pages 158-159

Introduction

1min
page 174

History

4min
pages 154-155

References

20min
pages 136-152

Conclusion

1min
page 135

Introduction

31min
pages 117-133

Containment or mitigation of COVID-19?

1min
page 134

References

40min
pages 99-116

Outlook

1min
page 98

Prevention

3min
pages 96-97

End of Quarantine

1min
page 95

Transmission Event

26min
pages 82-94

References

31min
pages 54-68

Summary

1min
page 69

Routes of Transmission

16min
pages 73-81

Outlook

3min
pages 52-53

The 2020 Lockdowns

7min
pages 48-51

Person-to-person transmission

2min
page 72

Special Aspects of the Pandemic

15min
pages 38-46

The SARS-CoV-2 pandemic: Past and Future

2min
page 47
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.