Strict self-isolation did not protect Swedish cancer patients on active treatment from the risk of becoming seropositive for SARS-CoV-2

Figures & data

Figure 1. Flow chart showing the inclusion process of personnel and cancer patients.

Figure 2. Description of method; study inclusion, collection of blood samples, serological analysis and statistical analysis.

Table 1. Clinical characteristics of 358 staff and 622 cancer patients included in the study, stratified by solid malignancy vs. hematological malignancy.

	Staff	All patients	p-Value staff vs. patients	Solid malignancy (SM)	Hematological malignancy (HM)	p-Value SM vs HM
Number (n)	358 (100)	622 (100)		475 (76)	147 (24)
Age (mean (range))	45.9 (19-74)	65.4 (18-95)	<0.001^b	64.3 (24-84)	66.5 (18-95)	0.07^a
Gender, n (% of total)
Male	58 (16.2)	268 (43.1)	<0.001^b	169 (35.6)	99 (67.3)	<0.001^b
Female	300 (83.8)	354 (56.9)		306 (64.4)	48 (32.7)
Treatment intention, n (%)
Curative	–	207 (33.3)	–	158 (33.3)	49 (33.3)	1.0^b
Palliative	–	415 (66.7)	–	317 (66.7)	98 (66.7)
Completed survey, n (%)
Yes	–	603 (96.9)	–	464 (97.7)	139 (94.6)	0.10^b
No	–	19 (3.1)	–	11 (2.3)	8 (5.4)
Place of birth, n (%)
Sweden	–	524 (84.2)	–	402 (86.8)	122 (87.8)	0.79^b
Europe	–	50 (8.0)	–	38 (8.2)	12 (8.6)
Other	–	28 (4.5)	–	23 (5.0)	5 (3.6)

^a t-test, ^b chi-square test.

Figure 3. Patients with hematological malignancies (HM, red line) and patients with solid malignancies (SM, green line) had a lower degree of SARS-CoV-2 seropositivity than health care personnel (blue line) (logrank test p = 0.082).

Table 2. Degree of anxiety vs. isolation and seropositivity, PCR-positivity and COVID-19-positivity in staff and patients; stratified by solid malignancy vs. hematological malignancy.

	Staff ^A	All patients	p-Value staff vs. patients	Solid malignancy (SM)	Hematological malignancy (HM)	p-Value SM vs. HM
Degree of anxiety, n (%)
None – mild	–	410 (68.0)	–	305 (65.7)	105 (75.5)	0.04^C
Moderate – high	–	193 (32.0)		159 (34.3)	34 (24.5)
Degree of self-isolation, n (%)
Not at all/partly	–	282 (46.2)	–	215 (46.3)	67 (42.4)	0.49^C
Completely	–	329 (53.8)		249 (53.7)	80 (57.6)
Non-invasive ventilation/intubation ^D, n (%)
Yes	–	26 (37.1)	–	14 (25.9)	11 (68.8)	0.005^C
No	–	44 (62.9)	–	40 (74.1)	5 (31.2)
Seropositivity, n (%)
Yes	58 (16.2)	60 (9.6)	0.005^C	50 (10.5)	10 (6.8)	0.24^C
No	300 (83.8)	562 (90.4)		425 (89.5)	137 (93.2)
PCR-positivity, n (%)
Yes	–	70 (11.3)	–	54 (11.4)	16 (10.9)	0.99^C
No	–	552 (88.7)		421 (88.6)	131 (89.1)
COVID-19-positivity ^B, n (%)
Yes	58 (16.2)	108 (17.4)	<0.001^C	89 (18.7)	19 (12.9)	0.19^C
No	300 (83.8)	514 (82.6)		386 (81.3)	128 (87.1)

SM: Solid malignancy; HM:Hematological malignancy.

^A Staff were not answering the questionnaire since self-isolation was impossible and 100% were working and not self-isolating ^B Overall COVID-positivity includes both PCR- and seropositive tests for patients, since patients with HM do not always become seropositive due to B-cell depleting treatments. Staff were considered immunocompetent, thus solely results for seroconversion were used and information regarding PCR-test results was not collected. ^C chi-square test. ^D PCR-positive patients requiring non-invasive ventilation or intubation during in-hospital care.

Table 3. Risk of seropositivity associated with degree of self-isolation gender, age, type of malignancy, treatment intention and place of birth.

	Univariable analysis			Multivariable analysis
	Number univariable analysis	OR univariable analysis	p-value univariable analysis	Number multivariable analysis	OR multivariable analysis*	p-Value multivariable analysis
Self-isolation
Strict vs no/partial isolation	602	1.40 (0.81, 2.48)	0.23	600	1.67 (0.94, 3.04)	0.09
Anxiety*
High vs no/mild	599	0.66 (0.34, 1.21)	0.20	–	–	–
Gender
Female vs male	622	0.79 (0.46, 1.35)	0.39	600	0.63 (0.35, 1.15)	0.13
Age
Continuous	621	0.99 (0.97, 1.01)	0.15	600	0.99 (0.96, 1.01)	0.34
Type of malignancy
Solid vs hematological	622	1.61 (0.83, 3.45)	0.19	600	1.99 (0.96, 4.59)	0.08
Treatment intention
Palliative vs curative	622	1.08 (0.62, 1.96)	0.78	600	1.12 (0.62, 2.09)	0.71
Place of birth
Born in Europe	602	0.81 (0.24, 2.09)	0.69	600	0.85 (0.25, 2.24)	0.76
Born outside Europe	602	1.11 (0.26, 3.32)	0.87	600	0.99 (0.22, 3.06)	0.98
Children in the household^¤
Yes vs no	622	1.91 (1.01, 3.47)	0.04	600	1.54 (0.70, 3.33)	0.27
Living alone
Yes vs no	602	0.46 (0.19, 0.99)	0.07	600	0.55 (0.22, 1.22)	0.17

OR: Odds ratio.

*Anxiety was not included in the multivariable model due to a strong correlation with self-isolation.

¤Children <18 years of age.

Figure 4. Risk of seropositivity for SARS-Cov-2 depending on degree of anxiety vs. degree of self-isolation. (a) a higher degree of anxiety did not affect the risk of SARS-CoV-2- seropositivity (p = 0.23). (b) Self-isolation did not affect the risk of SARS-CoV-2- seropositivity (p = 0.32).

Data availability statement

The data generated during the current study are not publicly available due to regulations on personal data protection but are available from the corresponding author on reasonable request.